Question

what is a recessive trait? a trait that is only expressed when two copies of the matching allele are present a trait that is always expressed over other traits a trait that is beneficial to a species a trait that is disadvantageous to a species

Explanation:

A recessive trait is defined by its genetic expression pattern. In genetics, alleles (gene variants) determine traits. A recessive trait requires two copies (homozygous recessive genotype, e.g., \( aa \) for a simple Mendelian trait) of the specific allele to be expressed. In contrast, a dominant trait (like the option "A trait that is always expressed over other traits") only needs one copy (heterozygous \( Aa \) or homozygous dominant \( AA \)). Whether a trait is beneficial or disadvantageous (\( 3^{rd}\) and \( 4^{th}\) options) is about its impact on the organism's survival and reproduction (related to natural selection), not its genetic expression pattern (which defines recessive/dominant).

Answer:

A. A trait that is only expressed when two copies of the matching allele are present