What is the distinction between cis and trans fats based on their structure?

The distinction between cis and trans fats primarily lies in the position of hydrogen atoms around the double bonds present in their fatty acid chains. In cis fats, hydrogen atoms are on the same side of the double bond, which creates a bend or kink in the fatty acid chain. This bent structure influences how the fats pack together, contributing to different physical properties such as melting points and solidity at room temperature.

In contrast, trans fats have hydrogen atoms on opposite sides of the double bond, allowing the fatty acid chains to remain straighter. This straight structure enables trans fats to pack more tightly, often resulting in a solid state at room temperature. Thus, the position of the hydrogen atoms is crucial for determining the properties and behaviors of these fats, making it the correct distinguishing factor in this context.

Other choices such as the type of fatty acid length, presence of double bonds, and amount of carbon atoms do not fundamentally differentiate cis from trans fats in the same specific manner that the positioning of hydrogen atoms does, which is why they are not the correct answer.