Over the rocky levels of the mountain was a streak of rust coloured air

Explanation

This is the problematic part. When used as a compound adjective to describe "air," it should be hyphenated as "rust-colored." This ensures clarity and correctness in modifying the nounThe correct answer is C) Rust coloured because the phrase should be hyphenated when used as a compound adjective.Explanation and Correction:To correct the hyphenation error:Hyphenate "rust coloured" to "rust-colored."Corrected Sentence:"Over the rocky levels of the mountain was a streak of rust-colored air."This correction ensures the compound adjective is correctly hyphenated, providing clear and accurate modification of the noun "air."