I believe the correct answer from the choices listed above is the second option. The expression (6.0 x 104) (3.1 x 10-1) is equal to 1.9 x 10^4. We only have two significant figures from the starting expression that is why we rounded of the product from 1.86 to 1.9.
That looks like cells of a multicellular organism, so B.
A triple beam balance is used to measure mass
