Step 1: Understanding the sentence.
The sentence "In his art class, Gyanendra learned how to paint, photograph moving subjects, and molding sculptures." contains an error with the phrase "moving subjects" when listing the activities. In parallel structure, the forms of the verbs should be consistent. The phrase "molding" should be corrected to match the form of the verbs "paint" and "photograph."
Step 2: Analyzing the options.
(A) In his: This part is correct and doesn't need any modification.
(B) how to: This part is correct. "How to" correctly introduces the infinitive verbs.
(C) moving subjects: Incorrect. This should be changed to "moving subject," as the plural form is inconsistent with the structure. The verb forms should be consistent throughout the sentence.
(D) molding: This should be changed to "mold," as it matches the structure of the sentence.
(E) No Error: This is incorrect because there is an issue with the parallel structure in the sentence.
Step 3: Conclusion.
The correct answer is (C) moving subjects, as "moving subject" should be used to maintain parallel structure with the other verbs in the sentence.