Which of these sequences represents the partial sums Sn=∑k=1n12kS_n = \sum_{k=1}^n \frac{1}{2^k}Sn=∑k=1n2k1 as n→∞n \to \inftyn→∞?
0.5,0.75,0.875,⋯→10.5, 0.75, 0.875, \dots \to 10.5,0.75,0.875,⋯→1
0.5,0.55,0.555,⋯→0.55‾0.5, 0.55, 0.555, \dots \to 0.5\overline{5}0.5,0.55,0.555,⋯→0.55
0.2,0.22,0.222,⋯→0.2‾0.2, 0.22, 0.222, \dots \to 0.\overline{2}0.2,0.22,0.222,⋯→0.2
1,1.5,1.75,⋯→21, 1.5, 1.75, \dots \to 21,1.5,1.75,⋯→2