Sperm and egg is responsible for reproduction?

Dna is colied into chromosomes in a cell

What do isotopes of uranium have the same number of? what do they have a different number of? a) same number of protons; different number of electrons b) same number of protons; different number of neutrons c) same number of electrons; different number of protons d) same number of neutrons; different number of protons

Has anyone taken the genetics unit test in connexus? not looking for answers, just a little bit what to expect and some with studying.