A singular noun names one person, place, thing, or idea. Mathematics is considered to be a singular noun.
Hence, the correct answer is A) Mathematics.
Mathematics is a noun which appears plura, but is actually singular in nature.
There are various other nouns like it, such as Physics, Ethics, Econonomics, ets.
Option 'B' gets ruled out
Option 'C and 'D' 'Maths' and 'Math' are the abbreviations of Mathematics, hence these options cannot be the right answer.