Answer: Choice C
Yes, holidays are a subset and proper subset of the calendar year.
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Explanation:
The set of days in the calendar year spans from Jan 1st to Dec 31st.
The set of holidays is a small subset of the previous set mentioned. Any holiday is found on the calendar, but not every day on the calendar is a holiday.
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Here's another example of a subset
A = set of all animals
B = set of dogs
Set B is a subset of set A because any dog is an animal. In other words, any individual in set B is also in set A, but not the other way around.
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Going back to the calendar example, the set of holidays is a subset and it's also a proper subset of all the days in the year. We say that set B is a proper subset of set A if B has less items in it compared to A.
If we had these two sets
A = {1,2,3,4,5,6}
B = {1,2,3}
We can see that B is a proper subset of set A since everything in B is found in A, and B is smaller than A. The only time we have a subset and not a proper subset is when we talk about the set itself. Any set is a subset of itself (not a proper subset of itself).
