In a Microbial Community,autotrophs Generate 1,000 Calories Per Hour of GPP

In a microbial community,autotrophs generate 1,000 calories per hour of GPP and 500 calories per hour of NPP.Primary consumers convert 60 calories per hour into their own biomass.What is the ecological efficiency in the link between autotrophs and primary consumers in this community?

A) 4 percent
B) 6 percent
C) 10 percent
D) 12 percent
E) 16 percent