Why are common names not a good reference to a species?

Would really appreciate it, i have an idea but not completely sure

In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar to a ) moss sporophyteb) moss gametophyte bearing both male and female gametangiac) fern sporophyted) fern gametophyte bearing only antheridia

Ineed to know why d is the correct answer asap