How many recessive alleles for a trait must an organism have to inherit that recessive phenotype? ? 1, 2, 3, or 4

Pairs of alleles can be either a 2 capital letters (such as AA), 2 lowercase letters (such as aa), or 1 capital and 1 lowercase letter (such as Aa).
To be dominant, an allele pair must have at least 1 capital letter. Any allele pair with both lowercase letters is recessive.

2 capitals (AA) is homozygous dominant. Homozygous because both letters have the same capitalization and dominant because there is at least 1 capital letter.
1 capital and 1 lowercase (Aa) is heterozygous dominant. Heterozygous because the letters have different capitalization and dominant because there is at least 1 capital letter. Heterozygous is always dominant.
2 lowercase (aa) is homozygous recessive. Homozygous because both letters have the same capitalization and recessive because both letters are lowercase, so there are no capitals.

So the answer is 2, there must be 2 recessive alleles for an organism to have that trait be recessive.