The correct answer is: If you saw the amount of Samosas he consumed at breakfast this morning, you would understand why he is so overweight.
The sentence is grammatically correct and makes sense. The word “if” is used to introduce a condition, and the word “saw” is used to describe the action of seeing. The word “amount” is used to describe the quantity of something, and the word “Samosas” is a type of food. The word “consumed” is used to describe the act of eating, and the word “breakfast” is a meal that is eaten in the morning. The word “this” is used to refer to the present time, and the word “morning” is a part of the day. The word “you” is used to refer to the person who is reading the sentence, and the word “would” is used to describe a hypothetical situation. The word “understand” is used to describe the act of comprehending something, and the word “why” is used to ask for a reason. The word “he” is used to refer to a man, and the word “is” is used to describe the state of being. The word “so” is used to describe a high degree of something, and the word “overweight” is used to describe a person who weighs more than is considered healthy.
The other options are incorrect because they do not make sense in the context of the sentence.