Explanation:

- Option 1: Secondary evidence

- This refers to evidence that is not the original document but is allowed in certain circumstances.

- Certified copies are generally considered secondary evidence because they are reproductions of the original.

- Option 2: Primary evidence

- This typically refers to the original document or the best evidence available.

- Option 3: Accepted evidence

- This is not a standard legal category of evidence, but rather a general term for any evidence a court might choose to accept.

- Option 4: Invalid form of evidence

- This would refer to evidence that is not admissible in court due to various reasons such as irrelevance or unreliability.

Answer 1: Secondary evidence

Certified copies are generally considered secondary evidence, making this the correct option.