Explanation:

- Statement (A): "He says that"

- This part is correct. It introduces what the person claims.

- Statement (B): "he has done engineering"

- This part is also correct. It indicates the person's educational background.

- Statement (C): "besides an MBA."

- This part is correct too. "Besides" effectively shows that the person has done something in addition to engineering.

- Option 1 (a): Refers to "He says that"

- No error here.

- Option 2 (b): Refers to "he has done engineering"

- Also, no error in this part.

- Option 3 (c): Refers to "besides an MBA."

- No error in this phrase as well.

- Option 4 (d): Indicates there is no error overall.

- Correct choice; there is no error in the sentence.