The first answer:
A (two-legged) driver is driving a (four-legged) horse. There are three people sitting in the car (3x2=6 legs). Each person carries three bags (3x3=9 bags). Each bag contains three big cats (3x9x4= 108 legs), and each big cat contains three kittens (3x9x).
So 2+4+6+108+324+972 =1416 legs.
The second answer:
Two legs: 1 driver +3 passengers =4 people; Four people take three bags, 4× 3 = 12 bags.
Quadruped: 1 horse; 3 big cats in each bag: 12 (bag) × 3 = 36 big cats; 36 big cats, 3 kittens each: 36× 3 = 108 kittens; 108 kittens have only 3 mice: 108× 3 = 324 mice. The total number of legs is equal to (36+108+324+1) × 4+4× 2 =1884 legs.
Note: it must be noted that each person carries three bags, the driver is human and there are three bags.
The third answer:
Horse: 1 four-legged horse.
People: 4 people with 8 legs.
Big cats: 4 people ×3 bags ×3 cats =36 cats ×4 legs -= 144 legs.
Kittens: 36 big cats× 3 =108× 4 legs =432 legs.
Mouse: big cat 36+ kitten 108 = 144× 3 = 432× 4 legs = 1728 legs.
Under the condition of no disability and no pregnancy, the total number of legs = 4+8+144+432+1728 = 2316 legs.
Of course, there are other answers. You can work out which one is correct.