Both the question and options given doesn't seem to be properly formatted. A well formatted form of the question is written in the comment section below.
Answer:
10a^4
Explanation:
Given the expression :
7a^4+3a^4
The sum of the expression given above could be taken directly Since the power of each individual value is the same.
7a^4+3a^4
Adding the coefficients
(7+3)a^4
10a^4