In a mouse body cell, the nucleus during G$_1$ phase of the cell cycle contains $1.2 \times 10^{-12}\,\text{g}$ of DNA. What is the mass of DNA in the nucleus of the cell at the end of S phase and at the end of G$_2$ phase?
- Aend of S phase: $1.2 \times 10^{-12}\,\text{g}$; end of G$_2$ phase: $1.2 \times 10^{-12}\,\text{g}$
- Bend of S phase: $1.2 \times 10^{-12}\,\text{g}$; end of G$_2$ phase: $2.4 \times 10^{-12}\,\text{g}$
- Cend of S phase: $2.4 \times 10^{-12}\,\text{g}$; end of G$_2$ phase: $1.2 \times 10^{-12}\,\text{g}$
- Dend of S phase: $2.4 \times 10^{-12}\,\text{g}$; end of G$_2$ phase: $2.4 \times 10^{-12}\,\text{g}$