Option 1 states that both the assertion (A) and the reason (R) are true, and that R is the correct explanation of A. To determine if this option is correct, we need to check if R explains A accurately.

The assertion states that adding water to an aqueous solution of HCl increases the pH. This means that the pH value becomes higher or more basic after adding water.

The reason given in option 1 is that adding water suppresses the ionization of HCl. To understand this reason, we need to know that HCl is a strong acid that fully ionizes in water to produce H+ ions. When water is added to the solution, it dilutes the concentration of HCl, leading to less ionization and fewer H+ ions, resulting in an increase in pH.

Therefore, option 1 correctly explains that the addition of water suppresses the ionization of HCl, which in turn increases the pH.

Option 2 states that both the assertion and reason are true, but R is not the correct explanation of A. However, this contradicts the explanation provided above, making option 2 incorrect.

Option 3, the provided correct answer, states that the assertion (A) is true, but the reason (