Problem: In 1870, republican sentiment in Britain, fed by the Queen's seclusion, was boosted after the establishment of the Third French Republic. A republican rally in Trafalgar Square demanded Victoria's removal, and Radical MPs spoke against her. In August and September 1871, she was seriously ill with an abscess in her arm, which Joseph Lister successfully lanced and treated with his new antiseptic carbolic acid spray. In late November 1871, at the height of the republican movement, the Prince of Wales contracted typhoid fever, the disease that was believed to have killed his father, and Victoria was fearful her son would die. As the tenth anniversary of her husband's death approached, her son's condition grew no better, and Victoria's distress continued. To general rejoicing, he pulled through. Mother and son attended a public parade through London and a grand service of thanksgiving in St Paul's Cathedral on 27 February 1872, and republican feeling subsided.
After what event did the Prince of Wales' health begin to improve?
The answer is the following: the tenth anniversary of her husband's death

Problem: Y-Gerät was the most complex system of the three. It was, in effect, an automatic beam-tracking system, operated through the bomber's autopilot. The single approach beam along which the bomber tracked was monitored by a ground controller. The signals from the station were retransmitted by the bomber's equipment. This way the distance the bomber travelled along the beam could be precisely verified. Direction-finding checks also enabled the controller to keep the crew on an exact course. The crew would be ordered to drop their bombs either by issue of a code word by the ground controller, or at the conclusion of the signal transmissions which would stop. Although its maximum usable range was similar to the previous systems, it was not unknown for specific buildings to be hit.
Which system was the most complex of the three?
The answer is the following: Y-Gerät

Problem: On the recovery side of the flight deck, the adaptation to the aircraft loadout is mirrored. Non-VTOL or conventional aircraft cannot decelerate on their own, and almost all carriers using them must have arrested-recovery systems (-BAR, e.g. CATOBAR or STOBAR) to recover their aircraft. Aircraft that are landing extend a tailhook that catches on arrestor wires stretched across the deck to bring themselves to a stop in a short distance. Post-WWII Royal Navy research on safer CATOBAR recovery eventually led to universal adoption of a landing area angled off axis to allow aircraft who missed the arresting wires to "bolt" and safely return to flight for another landing attempt rather than crashing into aircraft on the forward deck.
What does a landing area angles off access allow an aircraft to do if if misses the arresting wires?
The answer is the following: bolt

Problem: Following a headlining set at Coachella 2011 that was described by The Hollywood Reporter as "one of greatest hip-hop sets of all time", West released the collaborative album Watch the Throne with Jay-Z. By employing a sales strategy that released the album digitally weeks before its physical counterpart, Watch the Throne became one of the few major label albums in the Internet age to avoid a leak. "Niggas in Paris" became the record's highest charting single, peaking at number five on the Billboard Hot 100. In 2012, West released the compilation album Cruel Summer, a collection of tracks by artists from West's record label GOOD Music. Cruel Summer produced four singles, two of which charted within the top twenty of the Hot 100: "Mercy" and "Clique". West also directed a film of the same name that premiered at the 2012 Cannes Film Festival in custom pyramid-shaped screening pavilion featuring seven screens.
What festival did Kanye headline in 2011?
The answer is the following:
Coachella