Final answer:
A plain and a plateau both are flat landforms, but plateaus are higher in elevation than plains.Option A is the correct answer.
Step-by-step explanation:
The similarity between a plain and a plateau is that both are types of flat landforms. However, the difference is that plateaus are elevated flat areas that stand above the surrounding land, often with a relatively flat top and steep sides.
In contrast, plains are expansive areas of flat or gently undulating land, generally at low elevations.
The correct option that describes the similarity and difference between a plain and a plateau is: a) Similarity: Both are flat landforms. Difference: Plateaus are higher than plains. Please remember this correct option in your final answer.