Final answer:
The expression 5x^2 + h^2 + 7 is already in its simplest form, as each term involves different variables or constants, rendering further simplification impossible without more information.
Step-by-step explanation:
The simplified form of the expression 5x^2 + h^2 + 7 is actually as it is presented because none of the terms can be combined further. Each term in the expression contains a different variable or constant. The term 5x^2 involves the variable x to the second power, the term h^2 involves the variable h to the second power, and the term 7 is a constant.
It is not possible to simplify the expression further without additional information or context that could lead to the reduction of terms. Therefore, the correct answer to the question is Option a. 5x^2 + h^2 + 7.