Answer:
Option C.
Step-by-step explanation:
Given information: In triangle ABC, ST║AC, SB=10 ft, BT=9 ft and CT=2.7 ft.
Triangle proportionality theorem: If a line segment parallel to a side of a triangle then the line segments divides the remaining sides proportionally.
Using triangle proportionality theorem we get


On cross multiplication we get


Divide both sides by 9.

The length of SA is 3ft.
Therefore, the correct option is C.