A good source of vitamin A for pre-school children would be:

Cantaloupe pieces are an excellent source of vitamin A, particularly in the form of provitamin A carotenoids, which the body can convert into active vitamin A. Vitamin A is crucial for preschool children as it supports their growth and development, and plays a vital role in maintaining healthy vision, skin, and immune function.

In contrast, while grapes, watermelon, and bananas are nutritious fruits, they do not provide a significant amount of vitamin A. Grapes and watermelon primarily offer hydration and other vitamins and minerals, while bananas are known for their potassium content. Therefore, cantaloupe stands out as the best option due to its higher vitamin A content, making it especially beneficial for young children requiring ample nutrients for their growth and development.