A10 foot ladder is leaning up against a wall. the base of the ladder is 2 feet from the base of the building. how far up the building does the ladder fall?

See the picture attached to better understand the problem

we know that applying the Pythagoras Theorem
AC²=AB²+BC²
AC=10 ft
BC=2 ft
AB=?
AB²=AC²-BC²-----> 10²-2²-----> 100-4----> AC²=96
AC=√96  ft------> AC=9.80 ft

the answer is
 9.80 ft

The second and fourth answer are correct