Final answer:
An example of commensalism is cattle egrets eating insects disturbed by cattle. In this relationship, the cattle egrets benefit while the cattle remain unaffected. Commensalism occurs in various forms in nature, such as birds nesting in trees or bacteria on human skin. d) Wheat production declines in fields with large amounts of green foxtail grass
Step-by-step explanation:
Among the examples given, an example of commensalism is 'Cattle egrets walk beside cattle, eating insects disturbed by the movements of the cows.' In this relationship, the cattle egrets benefit by finding food more easily thanks to the activities of the cattle stirring up insects. The cattle, however, are neither positively nor negatively affected by the presence of the egrets. This is unlike other symbiotic relationships where both species may benefit (mutualism) or one benefits and the other is harmed (parasitism).
Commensalism can be observed in several other scenarios as well, such as when birds nest in trees. The trees are not harmed by the nests, and the birds benefit by having a safe place to raise their young. Similarly, Staphylococcus epidermidis bacteria live on human skin and consume dead skin cells, usually without harming or benefiting the host.