Correct Answer: dormant

Solution : The correct choice is the first option.

Dormant means inactive, and it is the correct word to convey the intended meaning that some promoters are active whereas others are inactive.

The meanings of the other options are as follows:

• Effectual: Capable of producing the desired effect or being effective.
• Productive: Yielding results or being fruitful.
• Lazy: Not active or functioning, often associated with being inactive or lethargic.

Therefore, the complete sentence is: Different cells express different proteins depending on which promoters are either active or dormant.