Two resistors of resistances $R_{1}=(100 \pm 3) \Omega$ and $R_{2}=(200 \pm 4) \Omega$ are connected in parallel. The equivalent resistance of the parallel combination is
(a) $(66.7 \pm 1.8) \Omega$
(b) $(66.7 \pm 4.0) \Omega$
(c) $(66.7 \pm 3.0) \Omega$
(d) $(66.7 \pm 7.0) \Omega$