Trong những cặp chất sau đây, cặp chất nào thuộc loại hợp chất carbonyl?

$\text{C}\text{H}{}_3\text{O}\text{H},\text{C}{}_2\text{H}{}_5\text{O}\text{H}$.

$\text{C}{}_6\text{H}{}_5\text{O}\text{H},\text{C}{}_6\text{H}{}_5\text{C}\text{H}{}_2\text{O}\text{H}$

$\text{C}\text{H}{}_3\text{C}\text{H}\text{O},\text{C}\text{H}{}_3\text{O}\text{C}\text{H}{}_3$.

$\text{C}\text{H}{}_3\text{C}\text{H}\text{O},\text{C}\text{H}{}_3\text{C}\text{O}\text{C}\text{H}{}_3$.