The correct option is C NaHCO3
The given reaction is an acid neutralization. Sodium bicarbonate (alkaline) is a component of antacids, which can neutralise the acid level of the stomach when a person experiences indigestion. The reaction will occur as follows:
HCl (aq)+NaHCO3(aq)→NaCl(s)+H2CO3(aq)
Therefore, X is sodium bicarbonate (NaHCO3).