Mendel crossed purebred purple-flowered plants with purebred white-flowered plants, and all of the resulting offspring produced purple flowers. The offspring are all , and the allele for purple flowers is .

A. heterozygotes, recessive
B. heterozygotes, dominant
C. homozygotes, recessive
D. homozygotes, dominant

Explanation:

As given pure bred purple plant is crossed with pure bred  white flower, their resulting flowers are all purple, it shows that purple is dominant over white.

So let purple as PP and white as pp

cross between PP and pp

PP×pp ; their gametes are Parent-1: P , parent -2, p

Offspring are: Pp, Pp, Pp, Pp

Here all offspring are heterozygous and the allele for purple color is dominant over white color.