在Ant Design of Vue中，设置带有图标的密码框正确代码是（）

A.<a-input placeholder="请输入密码"type="password"slot="prefix"><a-icon type="unlock"/></a-input>
B.<a-input placeholder="请输入密码"type="password"><a-icon slot="prefix"type="unlock"/></a-input>
C.<a-input placeholder="请输入密码"type="password"slot="prefix"type="unlock"><a-icon /></a-input>
D.以上都不对