Answer:
Option C.
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
![(SA)/(SB)=(CT)/(BT)](https://img.qammunity.org/2020/formulas/mathematics/high-school/f0fvxqk5aalkpp6sh9qq7ooaa1dxi8w6kr.png)
![(SA)/(10)=(2.7)/(9)](https://img.qammunity.org/2020/formulas/mathematics/high-school/ea40jp3qifhiiob98v0ttgwibdhct801ou.png)
On cross multiplication we get
![9* SA=2.7* 10](https://img.qammunity.org/2020/formulas/mathematics/high-school/82l5qvqljangcxlf5mny2t03vtquz108fh.png)
![9SA=27](https://img.qammunity.org/2020/formulas/mathematics/high-school/yp1kztd9ynnz0p1lpvi4hktc3zamrmwapq.png)
Divide both sides by 9.
![SA=3](https://img.qammunity.org/2020/formulas/mathematics/high-school/2ob94dd3cmki9t3kdu7ck7ljppkxlmpo0e.png)
The length of SA is 3ft.
Therefore, the correct option is C.