In Ulothrix/Spirogyra, reduction division (meiosis) occurs at the time of

Explanation

c. In Ulothrix/Spirogyra, reduction division (meiosis) occurs at the time of zygospore germination.Plant body of Ulothrix and Spirogyra, is gametophytic (haploid), they produce zoogametes (n) which fuses to form zygosporic (2n) diploid, which is a resting spore. Onset of favourable condition zygospore undergoes reductional division, or meiosis to produce zoo­meiospores During this stage of the life cycle, the zygospore, formed by the fusion of gametes, undergoes meiosis to produce new individuals. Other options are explanied below: a. Gamete formation: This is when haploid gametes are produced through mitosis and are later involved in sexual reproduction. d. Vegetative reproduction: This involves the growth and asexual reproduction of the alga, usually through fragmentation of the thallus, which does not involve meiosis..