Concept:Termites use chemical pheromones to prevent other colony members from becoming reproductively active.
Explanation:The original king and queen release a blocking pheromone that keeps other colony members non-reproductive.
When the original king and queen die, production of this blocking pheromone stops.
The suppression is lifted, so certain developing nymphs are specially nurtured.
These developing nymphs grow into secondary reproductives within the same colony.
The secondary reproductives then take over the role of the dead king and queen.
Answer:D. developing nymphs nurtured as secondary reproductives.