A distinctive characteristic of high-voltage radiography is that: 高电压照射后的射线底片的显著特征是:
选项：

A: it results in comparatively high subject contrast 它会产生相对较高的主因对比度
B: it results in comparatively high radiographic contrast 它会产生相对较高的射线底片对比度
C: it is applicable to comparatively thick or highly absorbing specimens 它可以应用于相对比较厚或高吸收的样件
D: there is no contrast in high-voltage radiography 高电压射线底片无对比度