What is a key factor in making Western Australia poorly accessible?

The correct answer highlights that geographic terrain plays a crucial role in determining accessibility in Western Australia. This region features vast stretches of arid desert, remote mountains, and rugged landscapes, which can significantly hinder transportation and infrastructure development. These geographical barriers make it challenging to establish roads, railways, and other forms of connectivity that would facilitate movement and accessibility for both people and goods.

In contrast, high population density would typically correlate with better accessibility due to increased demand for infrastructure. Urban development usually leads to improved transport networks and amenities, making areas more accessible. Low economic activity, while it may contribute to reduced infrastructure investment, is not as directly related to accessibility as the inherent challenges posed by the geography. Thus, geographic terrain is a decisive factor in the overall accessibility of Western Australia.