Consider the following statements:
Assertion (A): Plants are called primary producers.
Reason (R): Plants produce their food themselves through the process of photosynthesis.
Select the correct answer from the codes given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.