小红同学在用显微镜观察洋葱鳞片表皮细胞,显微镜的目镜有5×和l0×两种,物镜有l0×和40×两种,下列组合中观察到细胞数目最少的是( )
670-30____650
1000____99+1
75-26____50
36+64____100
Bob has got good exam results. His parents are proud of his ______.