Final answer:
The zygote of Toxoplasma gondii is diploid (2n), formed through fertilization of haploid gametes and capable of developing into the organism.
Step-by-step explanation:
The ploidy of the zygote during the life cycle of Toxoplasma gondii is diploid, which is indicated by 2n. In eukaryotic organisms, a diploid cell, such as a zygote, is formed through the process of fertilization, where two haploid (n) gametes merge. The resulting 2n zygote then has the capacity to develop into the organism through repeated rounds of cell division and growth.