Molecules move freely when there in gas form
The concentration of oxygen must be lower in the blood since diffusion is a form of passive transport, which goes down the concentration gradient (high to low.) Hope this helps! :)
Genetic drift is a random of sampling of alleles from the gene pool. if a chance of a forest fire for example kills all but two of the population, the maximum number of alleles two the individuals at as a single gene would be 4, if both heterozygous for different alleles, all the other ones would be lost and the remaining alleles would increase in frequency.
I am pretty sure that the only suitable option is the first one : a. meteoroid craters. This term was introdused by Francesco Maria Grimaldi<span>, who has a crater honorably named after him. If you still need the answer this one will definitely help you. Regards!</span>