Answer:
[tex]\boxed{\text{NaOH}}[/tex]
Explanation:
[tex]\rm \underbrace{\hbox{NaOH }}_{\hbox{base}} + \underbrace{\hbox{HCl}}_{\hbox{acid}} \longrightarrow \, NaCl + H$_{2}$O[/tex]
A hydroxide of a metal is a base.
[tex]\text{The base is }\boxed{\textbf{NaOH}}[/tex]
B is wrong. HCl is an acid.
C is wrong. NaCl is a salt.
D is wrong. Water is neutral.
