Which statement describes how a generator works? A. It transforms wire wrapped around a nail into a battery.
B. It uses an electric current in a magnetic field to produce motion.
C. It uses motion of a wire coil in a magnetic field to produce
electricity
D. It transforms electrical energy into mechanical energy.

It uses motion of a coil thru a magnetic field.

The energy produced is not free:

It takes work to move the wire thru the magnetic field to produce the electrical energy-- the efficiency of the generator would be:

the electrical energy produced / mechanical energy input

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =