He took up the letter from the table and ________ it aloud to his father.

The correct option to fill in the blank is Option C.

The sentence is in the simple past tense, which is used to talk about finished actions in the past. “He took up the letter” is a completed action, so the following action “read it aloud to his father” should also be in the simple past tense. 

Therefore, “read” is the correct choice. 

The other options “was reading”, “had read”, and “has been reading” are not in the simple past tense, so they don’t fit in this context.