What does an organism's phenotype describe? 1.) the allele combination for a trait
2.) the physical appearance of a trait
3.) the number of alleles on a gene
4.) the number of different traits inherited

2.) the physical appearance of a trait

Explanation:

An organism phenotype describes the physical appearance of a trait. Phenotypes are an outward expression of the genetic makeup of an organism.

Phenotype is usually conditioned by the environment in which an organism finds itself. Examples of phenotypes are the appearance of an organism, color, height, shape, etc. They are the observable traits of an organism. The genotype which is the genetic constituent of an organism controls the phenotypes.