Question

which diagram shows a planet with the least eccentric orbit?

Explanation:

Step1: Recall orbit - eccentricity concept

The less eccentric an orbit is, the more circular it is.

Step2: Examine the diagrams

Look for the diagram that most closely resembles a circle.

Answer:

The diagram that looks most like a circle (assuming one of the given diagrams is closest to circular in shape among them) shows the planet with the least - eccentric orbit. Since the actual diagrams are not fully visible in a way to definitively choose a numbered option, if we assume the most circular - looking one is numbered, we would choose that number. But based on the information given, we can only say to pick the most circular - looking diagram.