Permitió a los biólogos y médicos antiguos observar el mundo de lo diminuto a través de una de sus ramas, la óptica (microscopio). *

The answer is d because i just took the test

Yes i think so not 100 percent sure though

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water