Cho dãy các chất sau: (a) CH3OOC-CH2-COOC6H5; (b) CH3COO-CH2-COO-CH3

Cho dãy các chất sau: (a) $\text{C}\text{H}{}_3\text{O}\text{O}\text{C}-\text{C}\text{H}{}_2-\text{C}\text{O}\text{O}\text{C}{}_6\text{H}{}_5$; (b) $\text{C}\text{H}{}_3\text{C}\text{O}\text{O}-\text{C}\text{H}{}_2-\text{C}\text{O}\text{O}-\text{C}\text{H}{}_3$; (c) HO-CH₂-$\text{C}\text{O}\text{O}-\text{C}\text{H}{}_3$; (d) HOOC- $\text{C}\text{H}{}_2-\text{C}\text{O}\text{O}-\text{C}\text{H}{}_3$; (e) $\text{C}\text{H}{}_3\text{C}\text{O}\text{O}\text{C}\text{H}{}_2\text{C}{}_6\text{H}{}_5$; (f) $\text{H}\text{C}\text{O}\text{O}\text{C}{}_6\text{H}{}_5$. Với gốc $\text{C}{}_6\text{H}{}_5$ - là gốc phenyl. Số chất trong dãy tác dụng với NaOH theo tỉ lệ mol 1: 2 là