Solution
✅ Correct Option: 4
The phrase "count on one hand" is an idiomatic expression meaning "very few" that is used correctly here. The subject-verb agreement is proper throughout the sentence, and the clause structure is sound.
The complete sentence follows standard English grammar rules with a proper subject ("I"), verb ("could count"), and object structure. It expresses a complete thought in a grammatically correct way.
Therefore, the answer is: no errors (option D).