Crossing over... Occurs during prophase I
Is the exchange of genetic material between two homologous chromosomes
Produces genetic variations
All of the above

the answer is trees if i'm not mistaken

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.

answer; an inhibitory postsynaptic potential;

energy per photon is e = h*c / λ  

e = 6.63*10^-34 * 3*10^8 / 6*10^-7 j = 3.315*10^-19 j  

nr. of photons = 10j / 3.315*10 = ^-19 j per photon = 3.02*10^19 photons