Giải giùm e câu 20 ạ

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.

a. vertically

explanation:

i tried it and took the test

if im wrong then we have different tests