14. When one buys insurance, you need to be clear about your needs.

Question

__ Pronoun shift in number
__ Pronoun shift in person
__ Ambiguous reference
__ No error

Answer 1

You shifted from "one" to "you" . I would call that ambiguous

Answer 2

Yes, it's ambiguous, but the error is the second one. The pronoun "one" is 3rd person, but the pronoun "you" is 2nd person.

http://grammar.ccc.commnet.edu/grammar/consistency.htm
Scroll down to Pronoun Reference.