What is the primary force that suspension bridges use cables to hold their spans up? tension force resistance force normal force elastic force applied force

a) Tension Force

Explanation:

Since the platform suspended by the strings so here weight of the platform is counter-balanced by the force due to strings.

Here all the molecules of string has tendency to connect with each other so that the internal force between the molecules will help them to bound with each other.

Since we know that this force between the molecules are electromagnetic force due to electron sharing between each other

So this force is known as tension force between the molecules.

So here correct answer force the suspension bridges, cables will exert internal tensile force to counter-balance the weight of the platform.

So correct answer will be

Tension force