Answer:
Step-by-step explanation:
The tunnel, the ground and the depth of the tunnel form a right angle triangle.
The length of the tunnel is the hypotenuse of the right triangle that has been formed.
Let the length of the tunnel be .
Using the sine ratio, we obtain;
The length of the opposite side is
We substitute the given values to obtain;
We cross multiply to obtain;
Therefore the correct answer is C.