Choice 3 explains how one of the postulates in John Dalton's atomic theory was later subjected to change. Various scientists found that atoms consist of subatomic particles with varying mass and charge. This discovery led to the modification of Dalton's postulate that stated that all atoms of a given element are identical. The discovery of subatomic particles such as protons, neutrons, and electrons showed that atoms are composed of these particles, and different isotopes of an element can have varying numbers of neutrons while still belonging to the same element.