Answer:
a) Tall and purple
b) Tall and white
c) short and white
d) short and Purple
Explanation
when both alleles are same it is called homoozygous condition and when alleles are different it is called heterozygous condition
As tall(T) and purple(P) characteristics of plant are dominant so no matter whatever the alleles are,
TT or Tt its going to be tall
PP or Pp its going to be purple
TT and PP are Homoozygous Dominant
Tt and Pp are Heterozygous Dominant
but to get short or white both the alleles should be homoozygous recessive that is,
tt for short
pp for white