A. a back cross with a pure stock known to be recessive for that trait
B. a cross between two F, generations that are heterozygous for the trait
C. a testcross with a pure stock known to be dominant for the trait
D. in-breeding among the members of the species
E. out-breeding with an exotic variety of the species

Correct Answer:

Option A – a back cross with a pure stock known to be recessive for that trait

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