Biology · Kingdom Prokaryote

The following diagram shows reproduction by conjugation and it can be seen that the recipient forms a pilus at the end.

Sexual reproduction: Sexual reproduction involves the fusion of gametes (sex cells) from two individuals to produce offspring. While sex pili play a crucial role in bacterial reproduction, they are not directly related to sexual reproduction in the context of multicellular organisms. 

Binary fission: Binary fission is a form of asexual reproduction commonly observed in prokaryotic organisms, such as bacteria. In binary fission, a single bacterial cell divides into two identical daughter cells. During this process, the sex pili are not directly involved. 

Mitosis: Mitosis is a process of cell division that occurs in eukaryotic cells, leading to the production of two identical daughter cells. Mitosis is a part of the cell cycle and is crucial for growth, repair, and maintenance of multicellular organisms. Sex pili are not formed during mitosis. 

Conjugation: The correct answer is option (d) "Conjugation." Conjugation is a process of bacterial genetic exchange where genetic material (usually plasmids) is transferred between two bacterial cells via a structure called the sex pilus (or sex pilus). The sex pilus allows one bacterium (donor) to transfer its genetic material to another bacterium (recipient). Conjugation is one of the mechanisms of horizontal gene transfer in bacteria and plays a vital role in their genetic diversity and adaptation.