Geomorphic factors like slope angle, slope aspect, and relative relief directly influence the distribution of both plant and animal life in a particular ecosystem.

Option 1 suggests that only slope angle and relief have an influence. However, slope aspect also plays a crucial role as it determines the degree of sunlight exposure, affecting temperature and, ultimately, the types of species that can thrive there.

Option 2 suggests that slope aspect and relative relief influence distributions, but omits slope angle, which can affect soil depth and water runoff, again influencing which species can survive.

Option 3 includes slope angle, slope aspect, and relief but does not include "relative relief". Relative relief is the vertical difference in elevation between the high and low points in an area, which can influence species distributions by providing various ecological niches.

Option 4 includes all the geomorphic factors – slope angle, slope aspect, and relative relief – thus is the correct answer as it encompasses all elements that impact the plant and animal distributions in a habitat.