The correct answer is the first option: You should leave at least a day between anaerobic exercises to let muscles rest and heal.
Anaerobic exercises refer to exercises that involve short exertion periods along with high-intensity movement. In anaerobic exercise, the body's demand for oxygen is greater than the oxygen supply available. Due to this, the body relies on energy from muscles, rather than energy from oxygen. Since anaerobic exercises involve high intensity movement in muscles, muscles need at least a day's rest between anaerobic exercises to rest and heal.