The measurement of an unknown resistance \(R\) is to be carried out using a Wheatstone bridge. Two students perform an experiment in two ways. The first students take \(R_2=10~\Omega\) and \(R_1=5~\Omega\). The other student takes \(R_2=1000~\Omega\) ${\mathrm{}}_{}$and \(R_1=500~\Omega\). In the standard arm, both take \(R_3=5~\Omega\).
Both find \(R = \dfrac{R_{2}}{R_{1}} R_{3} = 10 ~ \Omega \) within errors.

 
Choose the correct option: 
1. (a, c)
2. (c, d)
3. (b, c)
4. (c, d)