Answer:
a. 1/64 AATTDD
b. 1/64 aattdd
c. 8/64=1/8 AaTtDd
d. 2/64 = 1/32 AATTDd or aattDd or AAttDd or aaTTDd
Explanation:
<u>Available data:</u>
- Flower position: Axial (A) is dominant to Terminal (a) 
- Stem length: Tall (T) is dominant to dwarf (t) 
- Seed shape: Round (R) is dominant to wrinkled (r) 
<u>Cross</u>: 
Parental) AaTtDd   x   AaTtDd
Knowing that these four genes assort independently, then we can infer that the F1 will have the next genotypic proportions for each gene:
        Aa =2/4
        aa = 1/4
         Tt = 2/4
          tt = 1/4
         Dd = 2/4
         dd = 1/4
<em>This is the same as developing a Punnett square for each gene separately.</em>
Knowing this, to get each of the mentioned genotypes for each trait, we must multiply their respective genotypic proportions, like this: 
a. homozygous for the three dominant traits, AATTDD
    AA1/4 x TT 1/4 x DD 1/4 = AATTDD 1/64 
b. homozygous for the three recessive traits, aattdd
    aa 1/4 x tt 1/4 x dd 1/4 = aattdd 1/64
c. heterozygous for all three characters, AaTtDd
    Aa 2/4 x Tt 2/4 x Dd 2/4 = AaTtDd 8/16=1/8
d. homozygous for axial and tall, heterozygous for seed shape. There are four possibilities, all of them with the same result:
AATTDd --> 1/4  x 1/4 x 2/4 = 2/64=1/32
aattDd ---> 1/4 x 1/4 x 2/4 = 2/64=1/32
AAttDd ---> 1/4 x 1/4 x 2/4 = 2/64=1/32
aaTTDd ---> 1/4 x 1/4 x 2/4 = 2/64=1/32