Fern spores are usually
Haploid
Diploid
Triploid
Tetraploid
A.
Haploid
In pteridophytes, spore is a haploid structure, which develops after meiosis in the spore mother cell. On germination, it gives rise to a green haploid prothallus (gametophyte) which is monoecious, i.e., has both antheridia (male sex organs) and archegonia (female sex organs).