Since humans can inherit a widow’s peak hairline or a straight hairline, the trait for hairline shape is an example of aaheritable characteristic with discrete variation bheritable characteristic with continuous variationcnon-heritable characteristic with discrete variation dnon-heritable characteristic with continuous variation

To determine the correct answer, let's break down the question and the options step by step:

1. Understanding the Trait:

   • The question mentions two types of hairlines: widow’s peak and straight hairline.
   • These are distinct categories, meaning the trait does not show a range but rather specific, separate forms.

2. Heritable vs. Non-Heritable:

   • Heritable characteristics are those that can be passed from parents to offspring through genes.
   • Non-heritable characteristics are not passed genetically and are usually influenced by environmental factors.

3. Discrete vs. Continuous Variation:

   • Discrete variation refers to traits that have specific, distinct forms (e.g., blood type, flower color).
   • Continuous variation refers to traits that show a range of forms, often influenced by multiple genes (e.g., height, skin color).

Given these definitions:

• Widow’s peak vs. straight hairline: These are distinct forms, so the variation is discrete.
• Heritable characteristic: The shape of the hairline is determined by genetics, so it is heritable.

Combining these points, the correct answer is:

a) heritable characteristic with discrete variation