Answer:
visual descent illusion
Explanation:
Visual descent illusion -
It is the process by which the people underestimate or ignores the height or depth of any object , when observing the object form very far away , but in actual context , the object might be very above or very low , is known as visual descent illusion .
Hence , from the question,
Marissa thought slope won't be that steep , but when she actual went near it , the slop was very steep , and she got panicked .