Inheritance of acquired characteristics is based on:

Explanation

Inheritance of acquired traits is when a parent uses a organ more/less than usual, hence changing certain aspects of it (for e.g. Giraffes stretched their necks to reach leaves on a tall tree, which was inherited by the offsprings leading to giraffes having longer necks), so inheritance of acquired characteristics is related to the use or disuse of organs, so Option B is correct. Physical traits rarely have a genetic role in inheritance (i.e. the genes that give rise to that trait are passed on and so play a part in reproduction but the trait itself does not have a genetic role). Survival of the fittest is related to natural selection and how frequently the trait is passed on to offsprings. Mutations are random changes in DNA sequence and so is not an acquired trait. So Option A, C and D are incorrect.