In other words, the use of similes can be a method of comparing two things. Let's look at some more examples: smooth as butter, light as a feather, and so on.
The sentence in the above-mentioned question attempts to draw a comparison between the person speaking (who requires glasses to see) and something or someone whose blindness is more obvious.
We have the option of using four animals to test the speaker's blindness, according to the solutions provided. Because bats are said to be blind, the appropriate simile to use is 'as blind as a bat.' As a result, "Option c" is the correct answer.

Bees are known to sting, so their simile is'stung sort of a bee'; beetles lack hearing capacity, so their simile is 'as deaf as a beetle'; and badgers have a white spot on their head that makes them appear bald, so their simile is 'as bald as a badger'.