<span>The correct answer is D. Only sentence D uses "mission" as a direct object.
By rewriting this question and changing the order a bit, it will become clear that "mission" is a direct object.
Consider: Sally Ride did fly which mission for NASA? The meaning of the sentence is the same as the original, but now we have put the parts of the sentence in an order that will help us identify the parts. Now we can easily see that the subject of the sentence is "Sally Ride." The verb of the sentence is "did fly." Finally, "mission" is the direct object.
In sentence A, "mission" is the subject of the sentence; in sentence B, "mission" is the object of the preposition "on"; and in sentence C, "mission" is also the object of the preposition "during."
Only in sentence D is "mission" a direct object.</span>
Personification and a surprise ending
The use of "Timothy" implies that Grandfather is merely taking his grandson to the zoo; however, the twist ending is that Timothy is a tiger. Suddenly the reason "no one would share a compartment with them" is all too clear-- no one would want to share a compartment with a large tiger.
The culture that this speech came from is a scared but family friendly one. Following the baby boom, nearly everyone in America have two+ kids and because of the cold war, people are constantly always fearful of a nuclear weapons attack. The author, President Kennedy, mainly uses ethos to get his point across.