Improved varieties of dogs, plants developed by :-Environmental selection    Natural selection     Artificial selection     Protective selection

Improved varieties of dogs and plants are developed by Artificial selection.

Here's the step by step explanation:

1. Artificial selection, also known as selective breeding, is when humans intentionally breed plants or animals for certain traits.

2. This process has been used for thousands of years in farming and pet breeding. For example, farmers might select for cows that produce more milk, or dog breeders might select for dogs with a certain appearance or temperament.

3. In the case of dogs, breeders might select for traits such as size, coat color, or behavior. Over many generations, this can lead to the development of distinct breeds with highly specialized traits.

4. Similarly, in plants, breeders might select for traits such as disease resistance, fruit size, or growth rate. This can lead to the development of improved varieties that are better suited to certain climates or farming practices.

5. Therefore, the improved varieties of dogs and plants are developed by artificial selection.