To find the length of the diagonal of a square, you can use the formula:
\[ d = s\sqrt{2} \]
where \(d\) is the length of the diagonal and \(s\) is the side length of the square.
Given that the side length \(s\) is 14 inches, the calculation for the diagonal would be:
\[ d = 14\sqrt{2} \]
Calculating \( \sqrt{2} \) approximately gives about 1.414. Therefore:
\[ d \approx 14 \times 1.414 \approx 19.8 \text{ inches} \]
So the approximate length of the diagonal of the square is 19.8 inches.
The correct answer is B. 19.8 inches.