Write the general term in the expansion of $(x^{2}-y)^{6}$.

• A
  $(-1)^{r} \cdot {}^{6}C_{r} \cdot x^{12-2r} \cdot y^{r}$
• B
  $(-1)^{r} \cdot {}^{6}C_{r} \cdot x^{6-r} \cdot y^{r}$
• C
  $(-1)^{r} \cdot {}^{6}C_{r} \cdot x^{12-r} \cdot y^{r}$
• D
  $(-1)^{r} \cdot {}^{6}C_{r} \cdot x^{2r} \cdot y^{r}$