Which of the following best describes a cost driver?

a$.$ A factor that causes a direct increase in the overall profit of a business.

b$.$ An element or activity that is directly responsible for the increase in the total cost of

a specific process or activity.

c$.$ A method used to allocate indirect costs to various products based on their use of

resources.

d$.$ A financial metric that measures the efficiency of resource utilization within an

organization.