Explanation:

- Option 1, a: "A man of fifty" is correctly framing the subject. No errors here.

- Option 2, b: "cannot be" is grammatically correct as it forms the negative modal. No errors.

- Option 3, c: The phrase "called as young" is incorrect. The correct phrase should be "called young" without the word "as".

- Option 4, d: "No error" would imply none of the parts have issues, which isn't the case here.