A particle covers half of its total distance with speed `v_1` and the rest half distance with speed `v_2`. Its average speed during the complete journey is.
A. `(v_(1)+v_(2))/(2)`
B. `(v_(1)v_(2))/(v_(1)+v_(2))`
C. `(2v_(1)v_(2))/(v_(1)+v_(2))`
D. `(v_(10^(2)v_(2)^(2))/(v_(1)^(2)+v_(2)^(2)))`