In a zygotic life cycle:
a. haploid cells form gametes that fuse to produce thick-walled diploid zygotes capable of surviving stressful conditions.
b. there is an alternation of generations.
c. the zygote undergoes meiosis and produces many heat-resistant spores that increase the population size and aid in dispersal.
d. haploid cells form spores that fuse to produce thick-walled zygotes capable of surviving stressful conditions.
e. none of the choices provided.

a. Haploid cells form gametes that fuse to produce thick-walled diploid zygotes capable of surviving stressful conditions.

Explanation:

The zygotic life cycle is exhibited by fungi and protists mostly. In these organisms, the multicellular organism is haploid. Haploid cells form gametes by mitosis. The haploid gametes are fused together to form the diploid zygote. Zygote mostly develops a thick wall to survive the unfavorable growth conditions. This zygote represents the only diploid phase of the life cycle of these organisms. Meiosis in zygote forms the haploid organism under favorable conditions.