A random person put the answer for you
I can help you with part 1
There are many combinations because it is not all about the number of chemicals, but also about the size of the strand. The longer the strand the more combinations there are and more variations and various lengths provide various results.
The answer is A it's a basic because once you add another substance to a neutral it either becomes acidic or basic. this one becomes basic because the hydroxide ion concentrate increased.