The figure below gives the schematic of the picture frame,
Since the frame is rectangular, so all the internal angles will be 90 degrees.
So the diagonal can be determined using Pythagoras Theorem as follows,
[tex]\begin{gathered} \text{Hypotenuse}^2=\text{ base}^2+\text{ height}^2 \\ \text{Hypotenuse}^2=7^2^{}+\text{5}^2 \\ \text{Hypotenuse}^2=\text{4}9+25 \\ \text{Hypotenuse}^2=\text{ 7}4 \\ \text{Hypotenuse}=\sqrt[]{74} \\ \text{Hypotenuse}\approx8.6 \end{gathered}[/tex]
Thus, the length of the diagonal is 8.6 inches approximately.
So the 4th option is the correct choice.
