This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

[Q]: Serotonin is a neuromodulator involved in regulation of mood and behavior. Development in the limbic system plays an important role in determining rewards and punishments and processing emotional experience and social information. Changes in the levels of the neurotransmitters dopamine and serotonin in the limbic system make adolescents more emotional and more responsive to rewards and stress. The corresponding increase in emotional variability also can increase adolescents' vulnerability. The effect of serotonin is not limited to the limbic system: Several serotonin receptors have their gene expression change dramatically during adolescence, particularly in the human frontal and prefrontal cortex .
[A]: Which neuromodulator is involved in regulation of mood and behavior?


[Q]: In addition to those actors who have headlined the series, others have portrayed versions of the Doctor in guest roles. Notably, in 2013, John Hurt guest-starred as a hitherto unknown incarnation of the Doctor known as the War Doctor in the run-up to the show's 50th anniversary special "The Day of the Doctor". He is shown in mini-episode "The Night of the Doctor" to have been retroactively inserted into the show's fictional chronology between McGann and Eccleston's Doctors, although his introduction was written so as not to disturb the established numerical naming of the Doctors. Another example is from the 1986 serial The Trial of a Time Lord, where Michael Jayston portrayed the Valeyard, who is described as an amalgamation of the darker sides of the Doctor's nature, somewhere between his twelfth and final incarnation.
[A]: Who played the War Doctor?


[Q]: Mexico’s capital is both the oldest capital city in the Americas and one of two founded by Amerindians (Native Americans), the other being Quito. The city was originally built on an island of Lake Texcoco by the Aztecs in 1325 as Tenochtitlan, which was almost completely destroyed in the 1521 siege of Tenochtitlan, and subsequently redesigned and rebuilt in accordance with the Spanish urban standards. In 1524, the municipality of Mexico City was established, known as México Tenochtitlán, and as of 1585 it was officially known as Ciudad de México (Mexico City). Mexico City served as the political, administrative and financial center of a major part of the Spanish colonial empire. After independence from Spain was achieved, the Federal District was created in 1824.
[A]:
What was the original name of Mexico City?