Q.Which of the following factors will favour species diversity?

Step 1. Consider each option's effect on species diversity. Invasive species (a) outcompete and displace native species, reducing local diversity, not favouring it.

Step 2. Glaciation (b) is a major disturbance associated with mass extinction events and reduced habitable area, which lowers species richness rather than raising it.

Step 3. Forest canopy (c) refers to the layered, structurally complex arrangement of a forest's foliage at different heights. This layering creates many distinct light, temperature and food microhabitats, allowing a much greater number of species to coexist by occupying different niches -- this favours species diversity.

Step 4. Coextinction (d) is itself a mechanism of biodiversity loss, since the extinction of one species drags down species obligately dependent on it, reducing diversity rather than favouring it.

Assess whether each listed factor tends to increase or decrease species richness/evenness in a habitat.

• Treating any ecological term in the list as automatically diversity-promoting.
• Confusing coextinction and glaciation (both loss-related) with genuine diversity-favouring factors.