Two conductors have the same resistance at `0^@C` but their temperature coefficient of resistanc are `alpha_1 and alpha_2`. The respective temperature coefficients of their series and parallel combinations are nearly
A. `(alpha_1+alpha_2)/2, alpha_1 + alpha_2`
B. `alpha_1+alpha_2, (alpha_1+alpha_2)/2`
C. `alpha_1+alpha_2, (alpha_1alpha_2)/(alpha_1+alpha_2)`
D. `(alpha_1+alpha_2)/2, (alpha_1+alpha_2)/2`