A、C4H8O2在稀硫酸中加热水解生成乙酸和乙醇,乙醇为CH3CH2OH,乙酸为CH3COOH,-CH3只有一种结构,所以酯只有1种结构,故A正确;
B、C6H12O2在稀硫酸中加热水解生成丙酸和丙醇,丙醇为CH3CH2CH2OH,丙酸为CH3CH2COOH,CH3CH2-只有一种,所以酯有2种结构,故B正确;
C、C8H16O2在稀硫酸中加热水解生成丁酸和丁醇,丁醇为C3H7CH2OH,丁酸为C3H7COOH,而C3H7-有CH3CH2CH2-和CH3CH(CH3)-2种,所以酯有2种结构,故C错误;
D、C10H20O2在稀硫酸中加热水解生成戊酸和戊醇,戊醇为C4H9CH2OH,戊酸为C4H9COOH,-C4H9有:-CH2CH2CH2CH3、-CH(CH3)CH2CH3、-CH2CH(CH3)2、-C(CH3)24种,所以酯有4种结构,故D正确;
故选C;