Answer: The right answer is the B) Add a comma after Dear Elizabeth and after Love.
Explanation: Just to elaborate a bit on the answer, it can be added that punctation in letters is very limited, but some rules apply. In American English, only the greeting in personal letters must be followed by a comma, as in the example (Dear Elizabeth,). However, the greeting in a formal letter takes a colon. In both American and British English, and in both formal and informal letters, the closing always requires a comma too (Love, or Yours sincerely,).