Which of the following would float in water at 25 ºc?
a. none of the other answers are applicable.
b. a substance with a density of greater than 1.00 g/ml.
c. a substance with a density of just greater than 1.00 g/ml.
d. a substance with a density of less than 1.00 g/ml.

d.A substance with a density of less than 1.00 g/mL.

Explanation:

The density of water, or of any fluid in which you immerse yourself, is directly proportional to the upward force that this fluid will exert on you. That is, the denser the water, the more you can float on it. This is the principle of Archimedes, with his famous Eureka.

In relation to the buoyancy of bodies, it does not depend only on the density of water, or fluid. Buoyancy also depends on the weight / volume of the body being submerged. In this case we are going to focus on the density of water / fluid.

In the case of water in conditions of temperature at 25 ° C the density is usually 1 g / ml so that any object that has a density less than it can float in it.

i think it's letter a.