Two rods having length `l_(1)` and `l_(2)`, made of materials with the linear coefficient of expansion `alpha_(1)` and `alpha_(2)` were welded together. The equivalent coefficients of linear expansion for the obtained rod:-
A. `(l_(1)alpha_(2)+l_(2)alpha_(1))/(l_(1)+l_(2))`
B. `(l_(1)alpha_(1)+l_(2)alpha_(2))/(alpha_(1)+alpha_(2))`
C. `(l_(1)alpha_(1)+l_(2)alpha_(2))/(l_(1)+l_(2))`
D. `(l_(2)alpha_(1)+l_(1)alpha_(2))/(alpha_(1)+alpha_(2))`
