Explain why the we use the letter v and v to represent the alleles for height in the above table:

Referring to the attached figure, there are two alleles V and v for height. The reason for using capital and small letters is to indicate the dominant or recessive nature of the allele.

Explanation:

Dominant (V):

An allele that is dominant means only one copy of that allele is enough for the expression of trait. For example, if V is for tall height, an individual with genotype Vv or VV both will have tall height because they have the allele of tall height that is dominant in nature.

Recessie(v):

An allele that is recessive nature means two copies of that allele are mandatory  for the expression of trait. For example, if v is for short height, an individual with genotype vv will have short height because they have two copies of same alleles that are recessive in nature. However if the genotype is Vv, still the individual will have tall height because capital letter is masking the effect of small letter (v allele). This is because of recessive nature of allele.

Hope it help!

the correct answer is b