单项选择题

A、当板厚h≤150mm时,间距不应大于200mm
B、间距S≥70mm
C、当板厚h>150mm时,间距不应大于1.5h,且不应大于250mm
D、当板厚h>150mm时,间距不应大于1.5h,且不应大于300mm