B ) ![H_2O]](/tpl/images/0350/9916/f8a53.png)
Explanation:- According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.
Amphoteric substances are substances which can act as both acids and bases and thus can accept and donate
ions.
![H_2O\rightarrow H^++OH^_](/tpl/images/0350/9916/24cbb.png)
Here water acts as an acid as it donates
ions.
![H_2O+H^+\rightarrow H_3O^+](/tpl/images/0350/9916/7f3da.png)
Here water acts as a base as it accepts
ions.