Which type of draft cooling tower would rely on mechanical assistance for air movement?

A forced draft cooling tower uses mechanical fans to draw or blow air through the tower, enhancing the air movement and improving the cooling efficiency. The mechanical assistance in air movement helps to maintain a constant airflow, regardless of external environmental conditions, which is crucial for the effective operation of the cooling system.

This type of cooling tower contrasts with naturally ventilated cooling towers, which rely solely on natural wind currents and thermal buoyancy for air movement, not involving any mechanical components. Counterflow and crossflow cooling towers can also operate without mechanical assistance but typically utilize fans for enhanced airflow in forced draft setups. Thus, the reliance on mechanical means for air movement is a defining feature of the forced draft cooling tower, making it the correct answer.