Can someone please help me answer my 9th grade biology questions?

If two parents who's blood types are both b produce a child that has blood type o, what can you say about the parent's genotybes? oa) one is ii ob) one is ibi oc) both are bi od) nothing, this is impossible

Areal dna molecule consists of thousands of these pairs of nucleotides. what is the pairing arrangement of the nitrogen bases

About how many years does it take for one cycle of surface water to become deep water and then surface water again in the oceans? 101001,000