The correct answer is option 'D': Arnon and Stout.

Explanation:

Importance of Essential Minerals for Plants:
Plants require essential minerals for their growth and development. These essential minerals are necessary for various physiological processes, such as photosynthesis, enzyme activation, and protein synthesis. Without these minerals, plants cannot complete their life cycle and exhibit stunted growth or nutrient deficiency symptoms.

Proposed Idea by Arnon and Stout:
In the mid-20th century, Arnon and Stout proposed the idea that plants require essential minerals for their growth. They conducted extensive research to determine the specific essential minerals needed by plants and their roles in plant physiology.

Research by Arnon and Stout:
Arnon and Stout conducted experiments using hydroponic culture systems, which allowed them to grow plants in nutrient solutions containing specific combinations of minerals. By manipulating the nutrient composition, they were able to identify the essential minerals required for plant growth.

Identification of Essential Minerals:
Through their research, Arnon and Stout identified several essential minerals for plants, including macronutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients such as iron, zinc, manganese, and copper. They determined the optimal concentrations of these minerals for promoting healthy plant growth.

Impact of Arnon and Stout's Work:
The research conducted by Arnon and Stout had a significant impact on the field of plant nutrition. Their findings provided a foundation for understanding the nutritional requirements of plants and helped in the development of fertilizer formulations to support plant growth. Their work also contributed to advancements in agricultural practices, leading to increased crop yields and improved food production.

Conclusion:
In summary, Arnon and Stout proposed the idea that plants require essential minerals for their growth and development. Their research identified the specific essential minerals needed by plants and their roles in plant physiology. Their work has had a profound impact on the field of plant nutrition and agricultural practices.