What type of ventilation is provided by mechanical means, such as electric fans?

The correct answer is identified as mechanical ventilation because it specifically refers to the use of mechanical systems, such as electric fans and HVAC units, to regulate and exchange air within a space. Mechanical ventilation can effectively remove indoor air pollutants, control humidity, and improve overall indoor air quality by actively forcing air to move in and out of a building.

This method contrasts with natural ventilation, which relies on natural forces like wind and temperature differences to circulate air. Active ventilation is a broader term that can include both mechanical and some forms of natural ventilation, but it does not exclusively denote mechanical systems. Passive ventilation, on the other hand, involves strategies that do not utilize mechanical systems, relying instead on building design to facilitate air movement. Thus, mechanical ventilation is the most accurate term for systems that utilize electrical means to ventilate a space.