Identical Twins Ilyse and Lauren Both Have a Gene for Trait

Identical twins Ilyse and Lauren both have a gene for Trait H. The gene for Trait H is expressed only when a child eats rice before the age of 2. Ilyse and Lauren are separated at birth, and Ilyse lives in Japan, where babies begin eating rice at an early age. Lauren lives in the United States, and she is not given rice before the age of 2. Ilyse develops Trait H, whereas Lauren does not develop the trait. This is an example of:

A) polygenic inheritance.
B) genotype-environment interaction.
C) phenotypical variety.
D) the dominant-recessive pattern of inheritance.