Fill in the blank with the most appropriate word.
He asked me what I was reading. "_________?" he asked me.
The two ways of relating what a person has said are 1)direct and 2)indirect (reported speech).In direct speech, the original speaker's exact words are repeated. In indirect/reported speech, the exact meaning is expressed but not necessarily using the original speaker's exact words. Pronouns and possessive adjectives usually change from first or second person to the third person except when the speaker is reporting his own words. Sometimes a noun can be inserted to avoid doubt.
When we turn direct questions and exclamations into indirect speech, they are converted to affirmative statement .( ? and ! is not used).
Option B is correct as when we convert the given indirect speech to direct question (use of what), the past continuous tense is changed to present continuous tense, me to you, and what is used at the beginning of the question.
The other options are wrong as do you, are you, and you were can't be used respectively.
The correct answer is B)What you are reading