单项选择题
下列样式定义字体间距为0.5倍间距、水平左对齐、垂直顶端对齐、有下划线正确的定义是:( )
A.p{text-decoration:underline; letter-spacing: 0.5em; vertical-align: top; text-align: left;};
B.p{text-decoration:0.5em; letter-spacing: underline; vertical-align: top; text-align: left;};
C.p{text-decoration: left; letter-spacing: top; vertical-align: 0.5em; text-align: underline;};
D.p{text-decoration:underline; letter-spacing: 0.5em; vertical-align: left; text-align: top;};