In odd-one-out (classification) questions, three items share a property and one does not. ASO asked them in 2012 (as jumbled words), 2018, 2021 and 2025.
Words
Find the most specific group that three items belong to. Parrot, Crow and Sparrow are birds, so Bat (a mammal) is out (ASO 2025). Lion, Tiger and Fox are carnivores, so Deer is out (ASO 2021).
Common groups: birds and mammals, carnivores and herbivores, metals and non-metals, fruits and vegetables, string and percussion instruments, cereals and pulses, places used for transport.
Jumbled words
Unscramble each word first (CWOR = CROW, CHTOSIR = OSTRICH), then classify them.
Numbers
Check in this order: prime, perfect square, perfect cube, even or odd, multiple of 7, 11 or 13, and digit sum.
Letter groups
Write the position numbers under each group and compare the gaps. The odd group usually breaks the gap pattern in one place.