Answer :
It wouldn't be I because the zygote is what is cause after the sperm and the ovum meet.
G isn't true because if the ovum's bad health is a cause of a miscarriage.
If I had to choose one it would be H, this is the only option that would make sense. As we all know, the sperm swims to the ovum and fertilizes it. So it would most likely be H.
Hope I helped. :)