Could you please tell me ?

a) how old you are b) are you how old c) how old are you d) you are how old

A

Explanation:

This sentence is the only grammatically correct answer. Why? In a direct question, you directly state your question, for example: "How old are you?"  When asking an indirect question (which is what this question is) you first start with a phrase such as "Can/could you tell me", then you add the direct question, but phrase the direct question as you would a statement, basically changing the word order: "Could you please tell me how old you are?"

The answer is not A it is C how old are you

c hydrophobia is the answer