Hello, ashik3140, and welcome to the Grammar Exchange.
Question: Does the picture relate to any important event in our national life?
answer:
(a) Yes, the picture relates to the Language Movement which is an important event in our national life.
(b) Yes, the picture is related to the language movement which is an important event in our national life.
The verb "relate" is one of many verbs that can be indistinctly used in the active (relates to ...) or in the passive (is related to ...). In the question, the verb is in the active form, so the same form should be used in the reply (answer (a)).
Supposing the Language Movement is an event, there should be a comma before the relative clause, because the antecedent is sufficiently defined:
(a) Yes, the picture relates to the Language Movement, which is an important event in our national life.