Can someone Please Help!!

If the ball is accelerating down through the air with no horizontal motion, the net forces acting on the ball must follow: C. The gravitational force is greater than the drag.

Explanation:

This is because the gravitational force is directed downward and the drag force opposes the direction of motion (therefore the drag force is directed upwards).  Since the ball is accelerating downwards, the gravitational force must be greater than the drag force in order to create this acceleration.

We know that the other options are incorrect because if the net force on the ball was directed upwards, the ball would be accelerating upwards.  If the net force on the ball was zero, the ball would not be accelerating at all.  If the drag was greater than the gravitational force, then the ball would be accelerating upwards as well.

Hope this helps!

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 =