Concept:Genetics is the branch of biology that studies heredity, genes, and variation.
Explanation:A scientist who specialises in the study of genes, heredity, and genetic variation is called a geneticist.
The term "geneticist" correctly describes a scientist who studies genetics.
Options like genealogist, mendalist, or genescientist are not standard scientific terms for this field.
Therefore, the correct choice is the one that directly names a genetics expert.
Answer:B. geneticist