what sentence describes all atoms of one element A. They have the same number of isotopes B. They have the same properties C. They have the same number of protons D. They have the same number of neutrons

C. They have the same number of protons.

Explanation:

Even though in isotopes, there's uneven number of neutrons, there's always same number of protons.

Hope it helps.

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong

the electron configuration that you gave me has 16 electrons ergo it has 16 protons ergo it is the element sulfur.