Concept:A prime number is a number greater than 1 with exactly two distinct factors: 1 and itself.
Explanation:- Option A: “All prime numbers are odd” is false because 2 is an even prime number.
- Option B: “There are infinitely many prime numbers” is true (e.g., 2, 3, 5, 7, 11, …).
- Option C: “A prime number has only two factors” is true.
- Option D: “There are only four single‑digit prime numbers” is true – they are 2, 3, 5, and 7.
- Therefore, the incorrect statement is Option A.
Answer:Option A (All prime numbers are odd numbers)