From the passage about personalised nutrition and genetic differences, answer the following question. Why, according to the passage, will one common diet not fit everybody in the future?

Introduction / Context:
This reading comprehension question focuses on a key idea from the passage: that a single diet plan cannot suit every individual. The passage explains how genes and metabolism differ from person to person, and how future diets will be personalised. The question asks for the specific reason given in the text for why one diet will not fit all.

Given Data / Assumptions:

• The passage discusses genetic differences between individuals.
• It mentions metabolism as another factor that varies from person to person.
• The scientist German is quoted as saying that one diet will not fit all.
• The question requires the exact reasoning given in the passage.

Concept / Approach:
The correct approach here is to identify the sentence or quotation that explains why one diet cannot be universal. The passage states that since people differ in their genetics and metabolism, one diet will not fit all. Any option that does not mention both genetics and metabolism, or that gives some unrelated reason such as mood, should be rejected. The task is to match the logic of the passage without distortion.

Step-by-Step Solution:
Step 1: Recall the line in the passage where German says one diet will not fit all. Step 2: Note the explanation connected to that statement: people differ in their genetics and metabolism. Step 3: Compare this explanation with option c, which states that people differ in genetics and metabolism, so their dietary needs are not the same. Step 4: Examine option a, which mentions different food habits but ignores genetic and metabolic differences, so it is incomplete. Step 5: Reject options b, d, and e, which introduce incorrect or off topic reasons that are not in the text.

Verification / Alternative check:
If we read the relevant part of the passage again, we see that it emphasises scientific reasons for diet differences, not social or emotional reasons. The text highlights inherited predispositions, genetic codes, and daily metabolism as key factors. Therefore, any correct answer must refer to these scientific elements. Option c is the only choice that matches this scientific explanation by naming both genetics and metabolism explicitly.

Why Other Options Are Wrong:
Option a talks about different habits, which may be true in real life, but that is not the reason the passage offers. Option b strangely claims that genes are identical and cause confusion, which is the opposite of what genomics emphasises. Option d mentions moods, which the passage does not tie to the question of why one diet will not fit all. Option e suggests that restaurants are responsible for diet diversity, which is clearly not part of the scientific argument. Because none of these options matches the passage, they are all incorrect.

Common Pitfalls:
A frequent error is to answer based on general knowledge or common sense about food choices instead of the specific reasoning used in the text. Another pitfall is to choose an answer that sounds plausible but leaves out key technical terms such as genetics and metabolism. When a passage uses scientific terminology, exam questions often expect students to include those exact concepts in their answers.

Final Answer:
According to the passage, one diet will not fit everybody because people differ in their genetics and metabolism, so their dietary needs are not the same, which is option c.