this is called a test
cross. since all the next generation flowers were red we can safely say
that the color red is dominant this is because the parent red flower can
either have a genotype of homozygous dominant RR or heterzygous Rr.
while the white flower has to be homozygous reccessive rr. since all the
offspring was red the genotype of the parent red flower is RR and red
is dominant over white.
hope this helps.........