Zygospore germination
the ulothrix or spirogyra has haplontic life cycle
if meiosis occur at the time of gamete formation the life should be diplontic life cycle as in case of fucus(rock weed) the asexual spores present in algae are zoospores so option b and d are not correct so option c is correct

Introduction:
Ulothrix and Spirogyra are both filamentous green algae belonging to the class Chlorophyceae. They undergo a type of sexual reproduction called conjugation, which involves the fusion of gametes to form zygospores. Reduction division or meiosis occurs during the process of gamete formation in both Ulothrix and Spirogyra.

Gamete formation in Ulothrix:
In Ulothrix, the vegetative filaments are haploid, meaning they possess one set of chromosomes. When conditions become unfavorable, the cells at the tips of two filaments differentiate into gametangia, which are specialized structures for gamete production. The gametangia in Ulothrix are called gametangial cells.

Process of gamete formation in Ulothrix:
1. Gametangial cells undergo mitotic division to produce numerous gametes.
2. These gametes are non-motile and are released into the water.
3. The male gametes are small and biflagellate, while the female gametes are large and non-motile.
4. Male and female gametes fuse together in a process called syngamy or fertilization, resulting in the formation of a diploid zygote.
5. The zygote develops a thick, resistant wall and becomes a zygospore.
6. Meiosis occurs within the zygospore, resulting in the formation of haploid cells called zoospores.
7. The zoospores are released from the zygospore and germinate to form new filaments.

Gamete formation in Spirogyra:
In Spirogyra, gamete formation also occurs during the process of conjugation, which is a type of sexual reproduction unique to filamentous green algae. Conjugation involves the fusion of two morphologically identical filaments to exchange genetic material.

Process of gamete formation in Spirogyra:
1. When conditions become unfavorable, two adjacent filaments come close to each other.
2. The cells at the tips of the filaments differentiate into gametangia, which are called conjugation tubes.
3. The conjugation tubes elongate and make contact with each other, forming a conjugation bridge.
4. The protoplasts from each filament move through the conjugation bridge and fuse together.
5. During the fusion, the gametes lose their flagella and become zygotes.
6. The zygotes develop a thick, resistant wall and become zygospores.
7. Meiosis occurs within the zygospore, resulting in the formation of haploid cells called zoospores.
8. The zoospores are released from the zygospore and germinate to form new filaments.

Conclusion:
Reduction division or meiosis occurs during gamete formation in both Ulothrix and Spirogyra. In Ulothrix, meiosis occurs within the zygospore, resulting in the formation of haploid zoospores. In Spirogyra, meiosis also occurs within the zygospore, leading to the formation of haploid zoospores. Both algae undergo these reproductive processes as a means of ensuring genetic diversity and survival in changing environmental conditions.