Explanation:

The pH scale measures the acidity or alkalinity of a solution, ranging from $0$ to $14$. A pH of $7$ is neutral, values below $7$ are acidic, and values above $7$ are alkaline (basic). A pH of about $10$ indicates a moderately strong base. Option (D) is correct because a sodium hydroxide ($\text{NaOH}$) solution, especially a dilute one, is a strong base and typically has a pH in the range of $10$ to $14$, depending on its concentration. Option (A) is incorrect; Gastric juice is highly acidic, with a pH typically between $1.5$ and $3.5$, due to hydrochloric acid. Option (B) is incorrect; Human blood has a very tightly regulated pH of about $7.35$ to $7.45$, which is slightly alkaline. Option (C) is incorrect; Milk of Magnesia is a suspension of magnesium hydroxide ($\text{Mg(OH)}_2$), which is a weak base used as an antacid, and its pH is typically around $10.5$, but a strong base solution like $\text{NaOH}$ is a more definitive example of a substance with a pH around $10$ or higher.