In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.

Comprehension:
A hummingbird’s brilliant throat colour is not caused by feather (1) ________, but rather by iridescence in the arrangement of the feathers. Light level, moisture, angle of viewing, wear and tear and other factors all (2) ______ just how bright and colourful the throat may appear. Hummingbirds cannot walk or hop, though their feet can be used to (3) _____ sideways while they are perched. These birds have evolved smaller feet to be lighter for more (4) ______ flying. They will use their feet for itching and (5) _______, however.