Form of reproductive isolation where two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water.

• A. Geographical Isolation
• B. Artificial Selection
• C. Karyotype
• D. Haploid

Answer: (A)

Geographic isolation occurs when physical barriers like rivers, mountains, or bodies of water split a population so individuals can’t mate with each other. This stops gene flow, and over generations the separated groups accumulate genetic differences due to mutation, drift, and distinct environmental pressures, eventually leading to reproductive isolation and, often, speciation. The other terms describe different ideas: artificial selection is human-guided breeding, karyotype refers to chromosome structure, and haploid denotes a single set of chromosomes, none of which capture the idea of a physical barrier dividing populations.