This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Subsets are sets within a set.
For example, if A = {1,2,3} , B = {1,2,3,4}
This would mean A is a subset of B, it is also a proper subset.
If we had Set C = {1,2,3,4}
Set C is a subset of B but not a proper subset. An empty set is also not a proper subset.
If all elements of a set are also elements of the other set...