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.

Example input: Passage: The French and Indian War (1754–1763) was the North American theater of the worldwide Seven Years' War. The war was fought between the colonies of British America and New France, with both sides supported by military units from their parent countries of Great Britain and France, as well as Native American allies. At the start of the war, the French North American colonies had a population of roughly 60,000 European settlers, compared with 2 million in the British North American colonies. The outnumbered French particularly depended on the Indians. Long in conflict, the metropole nations declared war on each other in 1756, escalating the war from a regional affair into an intercontinental conflict.
Example output: When was the French and Indian War?
Example explanation: This question is based on the following sentence in the passage- The French and Indian War (1754–1763) was the North American theater of the worldwide Seven Years' War. It is a common convention to write (start year-end year) beside a historical event to understand when the event happened. You can ask questions like this one about dates, years, other numerals, persons, locations, noun phrases, verb phrases, adjectives, clauses etc. which exist in the paragraph.
Q: Not all of the Luftwaffe's effort was made against inland cities. Port cities were also attacked to try to disrupt trade and sea communications. In January Swansea was bombed four times, very heavily. On 17 January around 100 bombers dropped a high concentration of incendiaries, some 32,000 in all. The main damage was inflicted on the commercial and domestic areas. Four days later 230 tons was dropped including 60,000 incendiaries. In Portsmouth Southsea and Gosport waves of 150 bombers destroyed vast swaths of the city with 40,000 incendiaries. Warehouses, rail lines and houses were destroyed and damaged, but the docks were largely untouched.
A:
Why were port cities targeted by the Luftwaffe?