The concept of 'Ecological niche' was first introduced by:

Correct option is A

Introduction
The concept of the Ecological Niche, a fundamental principle in ecology that defines a species' functional role and requirements within its environment, was first introduced by the American ornithologist J. Grinnel. 

Information Booster

• J. Grinnel (Joseph Grinnell), introduced the niche concept in 1917, focusing primarily on the physical and environmental conditions necessary for a species to survive and reproduce.
• Grinnell viewed the niche as a spatial unit or habitat, emphasizing the structural and physical adaptations of the species to its location.
• This initial concept is often called the "Grinnellian Niche."
• For Grinnel, the niche of a species was defined by where it lived and the set of conditions and resources required for its existence, such as climate, vegetation type, and nesting sites.

Additional Knowledge

Haeckel (Ernst Haeckel)

• He is famous for coining the term "Ecology" (Ökologie) in 1866, defining it as the study of the economy and relations of organisms to their surrounding environment.
• He did not introduce the niche concept.

Odum (Eugene Odum)

• A major twentieth-century ecologist, known for popularizing the concepts of the ecosystem and energy flow in ecological studies.
• He worked extensively with the niche concept but did not originate it.

The modern, widely accepted definition of the niche as an "n-dimensional hypervolume" was later formulated and popularized by G.E. Hutchinson in 1957. This definition integrates biotic interactions (food sources, competitors) in addition to the physical factors emphasized by Grinnel.