What is the ultimate source of genetic variation?

mutations

Explanation:

Mutations are changes in DNA sequence that can create genetic variation within the population and thus are the ultimate source of new alleles . Mutations are important for evolution because of their ability to form a new genetic variant (allele) that can be spread to the offspring.  If a new variant of a trait formed by a mutation is advantageous and helps the organism to survive and reproduce,  it is going to be favourable by natural selection. That  variation will more likely be passed to the next generation and remain over time.

the transfer for conduction is the heat transfering from the liquid to the spoon

the transfer for convection is the heat rising from the liquid to the air

the transfer for radiation is the heat going through the sides of the cup and to the air

at least that is what i would do