According to the Arrhenius Theory of acids and bases, a base is:

A A substance that decrease the amount of hydroxide ions present.
B A substance that increases the amount of hydroxide ions present when it is dissolved in water.
C A substance that increase the amount of hydrogen ions present.
D A substance that increases the amount of hydrogen ions present when it is dissolved in water.

D?

When reading "multiple guess" answers, one must be especially careful to read them and comprehend them fully. Profs sometimes get really tricky and throw in an extra word here and there which changes the entire complexion of an answer.

No.

Look up Arrhenius theory of acids and bases on google. Look in your notes. D is OK for and acid definition but not a base.

It states that Arrenheius theory increases the concentration of hydroxide, or OH-, ions in the solution when dissolved in water. So it would have to be C? Because I realize my teacher put B and D as the same answer choice which is confusing

Read your C answer again. It doesn't say anything about hydroxide ion.

I don't see B and D as the same. Perhaps you changed one of them if you thought they were the same.

Oh I'm sorry! My initial answer should have been B instead of D. I had read them as the same sentence on accident.

Thank you!

So the answer is B right?