Final answer:
The production of very slow delta waves during sleep occurs in NREM stage 3 sleep, which is characterized by low frequency, high amplitude brain waves.
Step-by-step explanation:
The stage of sleep marked by the production of very slow delta waves is known as NREM stage 3 sleep, or deep sleep. This sleep stage is characterized by low frequency (less than 3 Hz), high amplitude delta waves, which means this option corresponds to stage 3 sleep.
Regarding the associated learning objective question, sleep spindles and K-complexes are most often associated with stage 2 NREM sleep. REM sleep, by contrast, is marked by rapid eye movements and brain waves that are very similar to those observed in wakefulness, and it is the period during which most dreaming occurs.