Solve Square Root Multiplication: √1 × √25

To solve the expression $\sqrt{1} \cdot \sqrt{25}$, we will use the Product Property of Square Roots.

According to the property, we have:

$\sqrt{1} \cdot \sqrt{25} = \sqrt{1 \cdot 25}$

First, calculate the product inside the square root:

$1 \cdot 25 = 25$

Now the expression simplifies to:

$\sqrt{25}$

Finding the square root of 25 gives us:

$5$

Thus, the value of $\sqrt{1} \cdot \sqrt{25}$ is $\boxed{5}$.

After comparing this solution with the provided choices, we see that the correct answer is choice 3.