Ustilago is a genus of around 200 smut fungi parasitic on the grasses. In the haplontic life cycle, the haploid stage is multicellular whereas the diploid stage is a single cellular. The zygote undergoes meiosis to form the haploid spores. Each spore germinates are being divided to form gametophyte. The other three are not having this life cycle.
So, the correct answer is option D.