An organic molecule $X$ has the molecular formula $\text{C}_5\text{H}_{10}\text{O}_2$. Its infra-red spectrum shows a strong peak at $1250\,\text{cm}^{-1}$, another strong peak at $1720\,\text{cm}^{-1}$, but no strong peak above $3100\,\text{cm}^{-1}$. Which one of the following compounds could $X$ be?
- A1, 2 and 3
- B1 and 2 only
- C2 and 3 only
- D1 only