Answer:
(B) h is the function name; t is the input, or independent variable; and h(t) is the output, or dependent variable.
Explanation:
You've probably seen this function notation format before, most likely f(x). Other common ones are g(x) and p(x). The f, g, and p are just function names, like the h in this question.
The t in the parentheses is the input, because it's the same as the t in 210 - 15t.
Together, h(t) is the output, which is the exact same as y if you used the formula y = mx + b.
Hope it helps (●'◡'●)