I would say that B. is the right answer.
Step-by-step explanation:
we have a right-angled triangle :
the Hypotenuse (baseline opposite of the 90° angle) is the 850 ft cable from the top of the tower down to the point on the ground 360 ft away from the tower.
then the ground distance (360 ft) and the height of the tower are the 2 legs.
so, we can use Pythagoras
c² = a² + b²
with c being the Hypotenuse.
in our case
850² = 360² + height²
height² = 850² - 360² = 592,900
height = 770 ft
the tower is 770 ft tall.
