Isha of class IV asked her teacher, “Why cow does not lay eggs?” What is your most appropriate response if you are Isha’s teacher?

The correct option is: "Ask her to relate laying of eggs/giving birth to their visible ears and whose ears cannot be seen."

Explanation:
In primary science education (specifically Class IV), the goal is to encourage children to observe their surroundings and identify patterns rather than just memorizing facts.
An effective pedagogical approach to address Isha's question is to guide her to observe a simple, general rule of thumb in the animal kingdom:
1. Animals with external ears (ears that can be seen from the outside) and hair on their body (such as cows, dogs, cats, and humans) generally give birth to live young ones. These animals are viviparous.
2. Animals whose ears cannot be seen from the outside and do not have hair on their body (such as birds, frogs, lizards, and fish) generally lay eggs. These animals are oviparous.

By prompting Isha to relate the laying of eggs or giving birth to the presence or absence of visible external ears, the teacher encourages critical thinking, active observation, and scientific inquiry, allowing the student to discover the biological pattern herself.