Answer: C. 493 newtons
Explanation:
In the given picture, we have a right triangle in which the side opposite to the right angle is F (Hypotenuse of the right angle).
The other two sides are of 297 N and 394 N.
We know that Pythagoras theorem says that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.
Now by Pythagoras theorem we have,

Hence, the approximate total force, F = 493 N.