Logic: $3 \times 8 = 24, 3 \times 2 = 6$.

It's also an illogical question, therefore split 72 into 7 & 2 for finding out the logic from left to right and split 18 into 1 & 8 for finding out the logic from right to left. $(7+2) \times 2 = 18$ & $(5+6) \times 2 = 22$ (From Left to Right). $(1+8) \times 8 = 72$ & $(1+6) \times 8 = 56$ (From Right to Left). As 22 is not available as the answer choice here, therefore, logic from right to left will be chosen. 16 (From Right to Left).

Logic: $7^2 = 49, (7+2)^2 = 81$. Similarly, $8^2 = 64, (8+2)^2 = 100$.

Logic: $4 \times 5 = 20, 5 \times 6 = 30$. Similarly, $8 \times 9 = 72, 7 \times 8 = 56$.

Logic: $16 \times 3 = 48$ and $13 \times 3 = 39$. Similarly, $22 \times 3 = 66$ and $14 \times 3 = 42$.

Logic: $423 + 234 = 657$. Similarly, $534 + 234 = 768$.

Logic: $9^2-1=80, 100^2-1=9999$.

4 ⇒ 4²+3=19; 7 ⇒ 7²+3=52

5³+1=126; 8³+1=513

Logic: $12 \times 15/2 = 90, 16 \times 15/2 = 120$.

Logic: $1+2+3 = 6, 6^2 = 36$. Similarly, $2+2+1 = 5, 5^2 = 25$.

Logic: $5^2+5 = 30, 8^2+5 = 69$.

63-49=14, 49-35=14; 81-63=18, 63-45=18

1³, 2³, 3³; 4³, 5³, 6³

Logic: $2^3 = 8$ and $3^3+1 = 28$. Similarly, $3^3 = 27$ and $4^3+1 = 65$ (Option D).

Logic: $3 \times 6 \times 5 = 90$. Similarly, $6 \times 2 \times 3 = 36$ (Option A).

21-18=3, 18-12=6, 12-0=12; 32-28=4, 28-20=8, 20-4=16

Logic: $3^3=27, 3^2=9$. $4^3=64, 4^2=16$.

31-19=12, 31+19-9=41; 29-17=12, 29+17-9=37

4²=16, (4+3)²=49; 10²=100, (10+3)²=169