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.
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Now you can tell me wich is the closest number.
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