Question

cats accomplish this because their pupils – the openings that appear black in the middle of their eyes – are special. pupils operate like windows, with bigger ones letting more light into the eye. and a cat’s pupils can become up to 50% larger than human pupils in dim light. they also have a higher number of a specific type of light-sensing cell in the back of their eyes than we do. these cells, called rods, catch low-level light.
the tapetum lucidum
in addition to having large pupils and lots of rods, cats have something people don’t: a tapetum lucidum, a latin medical term that translates to “bright or shining tapestry.” the tapetum lucidum is also known as “eyeshine.”
5 it’s located in the back of the eye behind the retina – a thin layer of tissue that receives light, converts the light to an electrical signal, and sends this signal to the brain to interpret the image.
a cat’s tapetum lucidum is made up of cells with crystals that, like a mirror, reflect light back to the retina. this gives the retina a second chance to absorb more light.
the feline tapetum lucidum is special because its reflective compound is riboflavin, a type of vitamin b. riboflavin has unique properties that amplify light to a specific
question 25
by likening pupils to windows in paragraph 3, the author helps the reader understand –
a. how pupils allow light in.
b. how pupils protect against bright light.
c. how cats can control the size of their pupils.
d. how similar cats’ pupils are to humans’ pupils.

Explanation:

The relevant sentence in paragraph 3 (the highlighted part) says "Pupils operate like windows, with bigger ones letting more light into the eye". By comparing pupils to windows, the author is explaining the function of pupils in allowing light in, which matches option A. Option B is incorrect as there's no mention of protection against bright light. Option C is incorrect because the comparison to windows isn't about controlling pupil size. Option D is incorrect as the window comparison isn't about the similarity between cat and human pupils.

Answer:

A. how pupils allow light in.