Ms$.$ Ramos wants to increase the productivity of her bicycle parts factory. She has closely observed her employees at work and their output over the last sik months. As a rewit, the has noticed some trends.

Which trend demonstrates a direct causal relotienship?

Employees over $30$ years eld produce more parts than ysunger employees.

Employees profuct more parts during the week before they take a pald vacation.

Employees produce more parts during the week after they recelve their yearty evaluations.

Employees who use the new machine produce more parts than employees who use the old machine.