Parents that are heterozygous for having freckles (dominant) are crossed. which represents the ratio of their offspring?
twenty-five percent have freckles.
twenty-five percent are ff.
seventy-five percent have freckles.
seventy-five percent are ff.

The answer is Seventy-five percent have freckles.

Freckles are dominant trait. Gene responsible for freckles has two alleles (forms):
F - a dominant allele responsible for freckles
f - a recessive allele not responsible for freckles

Thus, genotypes are:
FF - dominant homozygote with freckles
Ff - heterozygote with freckles
ff - recessive homozygote without freckles

Heterozygous parents can give either dominant or recessive allele to the offspring. After heterozygous parents (Ff) with freckles will cross, 75% of the offspring will have freckles: one FF genotype and two Ff genotypes of total 4 genotypes. (3 out of 4 can be expressed as 3/4 = 0.75 = 75%).
Take a look at the above described possible genotypes and uploaded image of Punnett square in which with yellow are marked genotypes with freckles. 

Because they are stupid and insensitive

Mutations are changes in the dna