来自同一总体的两样本,下列哪个指标小的样本均数估计总体均数时更可靠
A <img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20230804/12258456_0.gif">+ B
CV C
S D
<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20230804/12258456_0_1.gif"> E
<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20230804/12258456_0_2.gif">