There are various________to this problem. We must try to find the best one. [ ]

A. ways  

B. accesses  

C. methods  

D. approaches

计算题：某山岭区一般二级路，变坡点桩号为K5+030，高程为427.68m，i₁=5%，i₂=-4%，竖曲线半径为R=2000m，计算竖曲线诸要素及桩号为K5+000和K5+100处的设计高程。