Consider the following statements :A. Atoms of each element emit characteristics spectrum.B. According to Bohr's Postulate, an electron in a hydrogen atom, revolves in a certain stationary orbit.C. The density of nuclear matter depends on the size of the nucleus.D. A free neutron is stable but a free proton decay is possible.E. Radioactivity is an indication of the instability of nuclei.Choose the correct answer from the options given below :