Which type of mutation is likely to have the least effect on an organism?

Point mutation (silent).

Explanation:

The term mutation refers to changes in genetic material, which is the main source of genetic variation.

One type of mutation is called a point mutation. This mutation occurs when only one nitrogen base is altered. Point mutations can be classified as silent, missense and nonsense.  The mutations are those in which a base is altered, but they do not affect the amino acid to be produced, that is, the code suffers alteration, however, the coded protein is the same, therefore, this type of mutation has a small effect on the organism.  On the other hand, in missense mutations, the amino acid of the protein is altered, producing a different one. The nonsense mutation, in turn, is one in which a termination codon is produced, preventing the protein from being produced integrally.

answer; polycythemia is the correct answer;