Answer:
B)chemical only
Explanation:
Now, it is important to understand that the reaction described in question is a neutralization reaction which is type of double displacement reaction. It is definitely a chemical reaction.
Now there is a difference between physical and chemical reaction. A physical reaction is one in which matter undergoes a physical change for example melting. In melting, a substance change its form but no change in the structure and composition of molecules occur.
On the other hand, in chemical reaction, change occur on molecular level. Old molecules convert into new molecular compositions. If you take example of Sodium Hydroxide and Hydrochloric acid here
NaOH + HCl → NaCl + H2O
Now you can see that both NaOH and HCl molecules decomposed into new molecules of H2O and NaCl.
Please notice that in physical reaction, no new substance is formed, but only physical appearance changes, that is why, we have to exclude third option "both physical and chemical".
