Best Answer Explained in Below-:

The correct answer is A) natural science because ecology is a branch of biological science that studies the relationships between living organisms and their environment. It encompasses the interactions between various forms of life, including plants, animals, and microorganisms, and how they relate to the physical environment around them.

Natural science, as a broader term, includes disciplines that seek to understand the natural world through observation and experimentation. These sciences often investigate the intricate web of life on Earth, making ecology a vital subfield within natural science.

In contrast, options B) weather, C) climate, and D) calamity do not appropriately represent ecology's focus. Weather refers specifically to atmospheric conditions at a given time, climate deals with long-term patterns of weather in a particular area, and calamity describes significant disastrous events, often human-made or natural disasters. Although these concepts can interplay with ecological studies, they do not encapsulate the core essence of ecology. Thus, A) natural science is the most accurate synonym for ecology.