A:Obviously; remains; proved `
B:Fundamentally; is remained; balanced
C:Traditionally; remaining; checked
D:Unbelievably; remains; settled
People in Colombia needn't make plans to meet their friends. They often just drop by them.
下列营养物质中,既不参与构成人体细胞,也不提供能量,而且人体的需要量也很小,但它对人体的作用却很大.该物质是( )