Complete analogous pair - Hill : Mountain : : Stream : ?

A. RIVER

The equations 4x + 7y - 10 =0 and 20x + 35y - 50 = 0 are :

B. CONSISTENT AND HAVE INFINITELY MANY SOLUTIONS.

Complete analogous pair - Oxygen : Burn : : Carbon dioxide : ?

C. EXTINGUISH

Complete analogous pair - Doctor : Nurse :: ? : Follower

B. LEADER

Complete analogous pair - Eye : Wink : : Heart : ?

B. THROB