Hi can someone help me?

i think they are all correct

explanation:

they seem good

a and c

c is 100% but i am confused in a

co2reflects heat radiation back to earth buning coal and oil emits co2 globe warms

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 =