Final answer:
A base coat is a colorless polish layer, applied to the natural nail to improve the adhesion of polish. It acts as a primer for the nail. Other types like top coat, nail hardener, and cuticle oil have different functions. So the correct answer is Option A.
Step-by-step explanation:
The colorless polish layer applied to a natural nail to improve the adhesion of polish is known as a Base Coat. This base coat acts as a primer for the nail, creating the ideal surface for the color polish to stick to. It's an essential first step in nail painting to ensure long-lasting and chip-free manicure. Top Coat is a type of nail polish applied after the color to give a shiny finish and seal the color. Nail Hardener is used to strengthen the nails, and Cuticle Oil is applied to moisturize the skin around the nails.
Learn more about Base Coat