Rocky bodies that orbit the sun but are not too small to be considered planets are known as :

a. meteors
b. comets
c. satellites
d. asteroids

D.) Asteroids

Asteroids are large rocks that orbit the sun.  They aren't considered planets since they are smaller.

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 =