If the strength of the magnetic field at b is 3 units, the strength of the magnetic field at a is a. 6 units b. 9 units c. 12 units d. 13 units

I think it is C. 12 units please tell me if im wrong

Correct Answer choice is C) 12! Hope this helped!

Explanation:

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 =