Directions: Four parts of the sentences given below have been underlined. Identify the part having an error. If no part has an error, mark (E).

Turquoise, (A) which is found in microscopic crystals, is opaque with (B) a waxy lustre, varying in (C) colours (D) from greenish grey to sky blue. (E) No error

The error is in part (C) "colours." In American English, "colours" is typically spelled "colors" (without the 'u'). While British English uses "colours," standard standardized testing in India typically follows American English conventions for spelling. The sentence should read "varying in colors from greenish grey to sky blue." This is a straightforward spelling error based on standard English conventions used in most academic and testing contexts.