Sexual processes in Protozoa — which is the most common method of sexual reproduction among protozoans?

Introduction:
Protozoa exhibit both asexual and sexual processes. This item distinguishes common sexual mechanisms from purely asexual cell division modes.

Given Data / Assumptions:

• Options include conjugation and various division terms.
• We must identify the most common sexual process.

Concept / Approach:
Conjugation, especially in ciliates (e.g., Paramecium), involves cell-to-cell pairing and micronuclear exchange, constituting a sexual process. Binary fission is asexual; “binary fusion” is not a standard protozoological term for sex in protozoa; gametangial contact describes fungal reproduction, not protozoan norm.

Step-by-Step Solution:

Verification / Alternative check:
Ciliate life-cycle descriptions consistently highlight conjugation as the sexual phase with genetic recombination.

Why Other Options Are Wrong:

• Gametangial contact: characteristic of fungi.
• Binary fission: asexual mitotic division.
• Binary fusion: not a standard protozoan sexual term.

Common Pitfalls:
Confusing frequent asexual fission (common overall) with sexual processes; the question explicitly asks about sexual reproduction.

Final Answer:
Conjugation