Answer:
All the progeny had a purple flowers in F1 generation.
Explanation:
A plant that always produced purple flower suggest that the plant is homozygous for purple color(PP) and the plant that always produces white flower then it is homozygous for white flower(pp) trait.
So when Mendel crossed these plants he saw that all the offsprings had purple flower which shows that purple is the dominant trait and white is the recessive trait.
P P
p Pp Pp
p Pp Pp
Therefore in first-generation, all the plants produced purple color flowers.