單項選擇題計算(8.2+6.21+6.21)×3.5,下面幾種計算方法中最簡便的方法是()

A.8.2×3.5+6.21×3.5+6.21×3.5
B.(8.2+6.21×2)×3.5
C.6.21×(2+1+1)×3.5
D.6.21×[(2+1+1×3.5)]