A cultured skin fibroblast cell of a goat ' $\mathrm{P}$ ' was fused with an enucleated ovum of a goat ' $\mathrm{Q}$ '. The resultant activated early embryo was then transplanted into a pseudopregnant (surrogate) female goat ' $\mathrm{R}$ ' of the same strain as ' $\mathrm{Q}$ '. On completion of gestation, a female goat ' $\mathrm{S}$ ' was born. With the exception of mitochondrial DNA, ' $\mathrm{S}$ ' is a clone of $\_\_\_\_\_\_\_\_$.
- Only $\mathrm{P}$
- Only $\mathrm{Q}$
- Only $\mathrm{R}$
- Both $\mathrm{P}$ and $\mathrm{R}$