Big Book Test 8: Section 5 Q:7

I went through Greg video explanation and earlier post on same to understand this problem more. I understood the first part of the sentence:

  1. “learning” in this sentence means what animals are learning and not what scientists are learning about animals. hence I was able to eliminate A,B and C.

But I still cannot understand what “sentence after the comma” even mean?
May you help me understand what does this even mean?

“learning as thoroughly stereotyped as the most instinctive of behavioral responses.”

Any help would be appreciated.
Thank you

This is how I understood it: