The correct answer is d) water.
Abiotic factors are the non-living components of an ecosystem that influence the living organisms within it. These include elements like sunlight, temperature, soil, water, and minerals. In this question, water is an abiotic factor because it is a vital component of an ecosystem that supports life but does not possess the characteristics of living organisms.
On the other hand, amphibians (a), wood (b), and mammals (c) are all biotic factors because they are living organisms or derived from them. Therefore, the presence and quality of water can greatly impact the survival and health of amphibians and mammals, but water itself is not a living entity.