"Controlling yourself" is perhaps most often used to mean controlling your temper, but is really means controlling all aspects of your personality, including your food intake.
This is a classic example of a test question formulated by someone who doesn't really understand the language. A strong case could be made for your answer, but the person administering the exam will only know one "correct" answer. Probably you know that B and D are not possible answers.
The best answer is A, because controlling intake is the key to keeping off holiday weight gain. There are "delicious foods" which do not cause weight gain, but let's face facts: most delicious foods do cause weight gain, which is why you responded as you did.
Funny the article suggests fast food as a way to avoid over-indulging. Fast food is notorious for being very high in calories.
Student or Learner