The correct answer is option 1: It is zero.

When a set of forces is said to be balanced, it means that the forces are equal in magnitude and opposite in direction. When this happens, the resultant force of the balanced forces is always zero.

To understand this concept, consider a scenario where two people are pushing a box with the same amount of force but in opposite directions. The forces that they apply cancel each other out, resulting in no net force on the box. Therefore, the resultant force is zero.

This principle applies to any set of balanced forces in physics. When the forces are balanced, the vectors representing the forces can be added together to find the net force, and in the case of balanced forces, the net force will always be zero.

In conclusion, when forces are balanced, the resultant force is always zero.