A balanced Wheatstone bridge ABCD has the following arm resistances:

R_AB = 1 kΩ ± 2.1% ; R_BC = 100 Ω ± 0.5% ; R_CD is an unknown resistance;

R_DA = 300 Ω ± 0.4%. The value of R_CD and its accuracy is

30 Ω ± 3 Ω

30 Ω ± 0.9 Ω

3000 Ω ± 90 Ω

3000 Ω ± 3 Ω

A balanced Wheatstone bridge ABCD has the following arm resistances: RAB = 1 kΩ ± 2.1% ; RBC = 100 Ω ± 0.5% ; RCD is an unknown resistance; RDA = 300 Ω ± 0.4%. The value of RCD and its accuracy is