Which of the following actions can reduce exposure to RF radiation?

RF radiation exposure decreases rapidly as you move further away from the radiating source, which in an amateur radio station is the antenna, not the transmitter itself. By relocating antennas higher up or further away from areas where people are present, you significantly reduce their RF exposure. Relocating the transmitter box inside the shack does not change the intensity of the RF field emitted by the antenna outside. Increasing the duty cycle (the percentage of time the station is actively transmitting) would actually increase average RF exposure, making it the exact opposite of a safety measure.