Explanation:

Correct option is 3: Neither she not 

- Option 1: "am going to take part"

- This part of the sentence is correctly structured. It uses the appropriate form of "to be" (am) for the subject "I."

- Option 2: "No error"

- This option would indicate that the sentence has no grammatical issues, but that is not the case here.

- Option 3: "Neither she not I"

- There's an error in this part. It should be "Neither she nor I" instead of "not." The conjunction pair should be neither/nor, not neither/not.

- Option 4: "in the debate competition"

- This part is grammatically correct. It correctly describes the event where participation is considered.