Short Answer 
The riddle plays with incorrect numbers of legs for animals and humans, stating a cow has 3 legs and a girl has 4, which is false. Understanding that cows have 4 legs and humans have 2 leads to the correct interpretation of the riddle.
Step 1: Understand the Riddle
The riddle presented mixes up the numbers referring to the number of legs that specific animals and humans possess. It states that ‘A cow has 3 and a girl has 4,’ which is incorrect. Recognizing that this is a playful twist on reality is the first step to solving the riddle.
Step 2: Know the Facts
To get the correct answer, you need to remember the basic biological facts about these creatures. A cow, as a quadruped, has:
- 4 legs
- It is a mammal known for being a livestock animal.
A girl, being a biped, has:
- 2 legs
- She is a human who typically walks upright.
Step 3: Interpret the Riddle Correctly
Upon understanding the correct number of legs each has, it becomes clear that the correct statement should read ‘A cow has 4 and a girl has 2.’ This change reflects the true situation and resolves the riddle correctly.