What genetic condition is characterized by expression only when the gene is present on both chromosomes?

The correct choice highlights the concept of recessive traits in genetics. A genetic condition characterized by expression only when the gene is present on both chromosomes exemplifies a recessive inheritance pattern. In this scenario, an individual must inherit two copies of the recessive allele—one from each parent—for the associated condition or trait to manifest.

For example, in the case of recessive disorders like cystic fibrosis or sickle cell anemia, an individual must have two mutated alleles (one from each parent) to express the disorder. If only one mutated allele is inherited, the individual remains phenotypically normal, showing that the recessive trait does not manifest unless both alleles are present.

Focusing on the other options, while conditions like albinism, sickle cell anemia, and cystic fibrosis illustrate conditions that can follow recessive inheritance, the term "recessive traits" encompasses this definition more broadly, making it the best answer to the question about genetic expression when the gene is present on both chromosomes.