Answer:
В.) Their car is in the shop, so they will be flying to Vermont and then to Florida
Step-by-step explanation:
A.) is incorrect because "their" is used to describe something belonging to someone. The accurate form is "they're", the contraction of "they are". "Their" is used before a noun, whereas "they're" is used before a verb.
B.) is correct because the following word is a noun that belongs to the people described in the sentence.
C.) is incorrect for the same reason as described in A.)
D.) is incorrect because a noun belonging to Kerry is not being described. The accurate form is "there" as the sentence is indicating a place.