Choose or find odd pair of words - (Atom : Electron) , (Train : Engine) , (House : Room) , (Scooter : Gears) , (Curd : Milk)

A. CURD : MILK

Choose or find odd number - 21 , 69 , 81 , 83

C. 81

Choose or find odd letter group - EFGIK , CDFIM , BCEHL , ABDGK

A. EFGIK

Choose or find odd pair of words - (Cow : Calf), (Dog : Bitch), (Lion : Cub), (Tortoise : Turtle), (Insect : Larva)

B. DOG : BITCH

Choose or find odd letter group - RUX , GJM , YBE , ZCF , NPS

E. NPS