In the right triangle ABC
AB and BC are the legs of the right angle
AC is the hypotenuse
The relationship between them is
[tex]AC=\sqrt{AB^2+BC^2}[/tex]Since AB = 6
Since BC = 4
Substitute them in the rule above
[tex]\begin{gathered} AC=\sqrt{6^2+4^2} \\ \\ AC=\sqrt{36+16} \\ \\ AC=\sqrt{52} \\ \\ AC=2\sqrt{13} \end{gathered}[/tex]The correct option is a