Concept:
Evaluating Assertion and Reason questions requires determining the factual accuracy of both statements independently, and then assessing if the Reason is the direct, primary cause of the Assertion.
Step 1:
After graduating from Santiniketan in 1944, Devi Prasad did indeed join Mahatma Gandhi's ashram at Sevagram (Sewagram). He worked extensively on "Nayi Talim" (New Education), focusing on child art, and edited a journal by the same name until he left for London in 1962. Thus, Assertion A is correct.
Step 2:
Devi Prasad was an active participant in the Indian independence struggle, specifically the Quit India Movement which began in 1942. His association with Gandhian principles during this era (1942-1947) is historically documented. Thus, Reason R is correct.
Step 3:
Why did Devi Prasad work on child art and education at Sewagram? The direct cause was his specialized background—he had just graduated from Kala Bhavana with a deep understanding of art education, combining Tagore's artistic vision with Gandhi's educational framework.
Step 4:
While Reason R provides the broad political context of his association with Gandhi, it does not specifically explain why he was the person teaching child art and editing the educational journal. His artistic degree from Santiniketan is the actual explanation for his specific role described in A.
Step 5:
Since both statements are factually true but the second does not directly explain the specific actions in the first, Option 2 is correct.
\[
\boxed{\text{(2) Both A and R are correct but R is NOT the correct explanation of A.}}
\]