True-breeding pea plants always

b

produce offspring with only one form of a trait.

produce offspring with either form of a trait.

are heterozygous.

are pollinated by hand.

d

When a single trait is being studies, a test cross is a cross between an individual with the dominant phenotype but of unknown genotype (homozygous or heterozygous) with a homozygous recessive individual. If the unknown is heterozygous, then approximately 50% of the offspring should display the recessive phenotype.