Read this sentence from paragraph 2 of the passage.

“The principle behind biomimicry is not simply to copy nature, but to look at the designs that we can see in nature and use those designs to help solve human problems.”
What is the relative clause in this sentence?

“that we can see in nature”

“principle behind biomimicry”

“simply to copy nature”

“to help solve human problems

“that we can see in nature”