Atomic radii increases down the group even though the nuclear charge increases. explain​

i'm assuming that the correct answer is indeed the first one/ "a"..

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.