Answer:
The correct answer would be "there is a reduction in the availability of nutrients away from the cost, which decreases primary production. Fewer producers and energy are available, leading to a decrease in biomass".
As we move in depth and distance from the coast the availability of sunlight decreases.
Thus, the number of primary producers would decrease as they would be unable to perform photosynthesis.
Consequently, the number of nutrients available at that depth would be very less as compared to the coast.
Hence, the carrying capacity of the region would be less which ultimately decreases the biomass.
