Determine the common ratio rrr of a geometric sequence where a1=1a_1=1a1=1 and S3=1+r+r2=1.75S_3 = 1+r+r^2 = 1.75S3=1+r+r2=1.75.
0.50.50.5
1/31/31/3
0.250.250.25
2/32/32/3