What is the minimal number of nymphal stages a bed bug must undergo before reaching adulthood?

Bed bugs experience a series of life stages, transitioning from an egg to a nymph and finally to an adult. For a bed bug to reach adulthood, it goes through multiple nymphal stages, specifically five distinct stages. Each of these nymphal stages requires a molt, and the bed bug needs to feed at least once between each stage to grow and develop properly.

Thus, the correct answer is based on the understanding that a bed bug must complete five nymphal stages, which are critical for its maturation process and survival. This knowledge of the life cycle is important for effective pest management strategies, as it helps identify the most vulnerable points for treatment and control measures.