A - Vinegar - Acid
B - NaOH- Base
C - HCL - Acid
D - HNO3 - Acid
NaOH is a base because when it is dissolved in water it dissociates into Na+ and OH- ions. When it had OH- ( hydroxyl ion ) ions, it automaticly is a base; thus, NaOH must be a base.
Hope this helps! :)
