Ecological role of elephants - logical inference

The author cataloges the massive, foundational ecological roles played by elephants: creating vital clearings , spreading seeds across regions [cite: 3346, 3347], manufacturing nutrient-rich dung for smaller lifeforms [cite: 3347, 3348], and digging water wells that sustain alternate wildlife during droughts. An organism whose singular presence structurally shapes, sustains, and anchors an entire ecological community is defined as a "keystone species". This maps directly onto option (b). Option (c) is a trap containing a strict negative absolute ("cannot be maintained"), while option (d) attributes a calculated intent ("as per their requirement") that distorts basic animal behavior.

Answer: (b).