Answer:

a ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎ ︎

Answer:

c

Step-by-step explanation:

because the other sets have different classifications just like a there are many kinds of colors, b there are different officers in school and d, there are many classifications of books like their genres. That is why c is a well defined set because sets of even numbers from 1-10 are numbers which are wll defined

that is my opinion po.. hope it helps:)