Question

Photosynthesis is ___________ reaction, because it needs sunlight to proceed.
a. an exothermic
b. an electric
c. an endothermic
d. a combustion

Answer 1

This is suppose to be a Biology Question, not in Physics.

Anyway, Combustion is an internal explosion produced from ignited fuel within an enclosure, and Electric reaction requires... well, electricity—so both of those DO NOT apply:

You're left with Exothermic and Endothermic.

Since Photosynthesis occurs "within" the leaves or other parts of a Plant, takes in energy from it's surroundings in the form of Solar rays and creates reactions from within, which process do you think it is doing, Exothermic, or Endothermic?

(Endothermic is the process in which a system makes reaction "Within", from the inside of the system taking energy from the outside;

while Exothermic is the process in which a system makes a Reaction from the "outside", using energy from within the system.)