Which of the following is true about sex pili?

Ans: c (Hollow tubular structure) Ref Ananatha7th ed, p. 16Sex pili are hollow conjugation tubesThey are found in male bacteria and it helps in attachment to female bacteria.Genetic material is transferred from the donor to the recipient cell.There may be a doubt that choice b "transfer plasmid only" is also correct but the choice c i.e. sex pili is a tubular structure is absolutely correct. So among the given options choice c would be the better answer.