The answer is, "c","4.0 ft".
if we draw a line at center, now it makes two triangles and the total length of the bottom is 6, so split that in half, which is 3.
Now, by using Pythagorean theorem, a² + b² = c²
Now b = 3 and given that c = 5
a² + 3² = 5²
a² = 25 - 9
a² = 16
a = 4
Thus, the height of his tent at the tallest point is 4 ft.