Hemophilia is a sex-linked trait. If a man and a woman have a hemophilic son, which of the following MUST be true? a)The father is a carrier

b)The mother is a carrier

c)The boy's grandfather has hemophilia

d)Both parents have the disease allele

If Hemophilia is a dominant trait then the mother or father could've passed down that gene. Assuming that Hemophilia is a ressecive gene then both parents must have the ressecive gene and passed it down to their son.

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

b. lithosphere, asthenosphere, mesosphere   is the answer most likely