由A、B点的高程HA=100米、HB=200米，求高差hAB ＝(      )米。

A、<span style=";font-family:宋体;font-size:16px"><span style="font-family:宋体">＋</span><span style="font-family:Times New Roman">100</span></span></p><p></p>

B、<span style=";font-family:宋体;font-size:16px">&nbsp;<span style="font-family:宋体">－</span><span style="font-family:Times New Roman">100</span></span></p><p></p>

C、<span style=";font-family:宋体;font-size:16px"><span style="font-family:宋体">＋</span><span style="font-family:Times New Roman">200 &nbsp; &nbsp;</span></span></p><p></p>

D、<span style=";font-family:宋体;font-size:16px"><span style="font-family:宋体">＋</span><span style="font-family:Times New Roman">300</span></span></p><p></p>