Explanation:

- Documents improperly procured (option a): These are documents obtained in a manner that may not follow proper procedure, but generally, the manner of procurement does not affect admissibility. Courts focus on relevance and authenticity.

- Documents procured by illegal means (option b): Even if a document is obtained illegally, it is usually still admissible in evidence if it is relevant, except in rare cases where law specifically excludes it.

- Both (a) & (b): Since both improperly and illegally obtained documents can still be admitted, selecting both would mean both are not admissible, which is generally not correct.

- Neither (a) nor (b): This means both types of documents are generally admissible, which aligns with how courts mostly operate.

Option:4- neither (a) nor (b).