Step 1: Understanding the Reaction.
The problem describes a reaction involving alkyl groups R', R'', and R''', which is likely a reaction where the organic molecule undergoes substitution or addition, leading to the formation of a new product.
Step 2: Analyzing the Options.
- (A) \( R' = \text{CH}_3, R'' = \text{CH}_3, R''' = \text{CH}_2\text{CH}_3 \) is the correct product formed from the reaction based on the structure.
- (B), (C), and (D) are incorrect because they involve incorrect alkyl substitutions.
Step 3: Conclusion.
The correct answer is (A) \( R' = \text{CH}_3, R'' = \text{CH}_3, R''' = \text{CH}_2\text{CH}_3 \) as it correctly represents the product of the given reaction.