Yhe phase you are describing is the lag phase.
Two atoms that have the same number of protons but different number of neutrons are called isotopes. Atoms with the same element but with a different number of neutrons.
The correct answer is the second choice, "Two identical prokaryotic cells."
Binary fission happens when bacterial cells copy chromosomes and split into two. It's most common in prokaryotic cells, but can happen in some eukaryotic cells.
