15. Why do people like frames made of titanium? (A) it is light. (D) it is flexible. (B) it is cheap. (E) it is scratch resistant. (C) it is strong. 16. We know from the text that __ (A) visibility can be significantly reduced when the temperature changes rapidly. (B) titanium is the lightest frame. (C) scraping and fracturing require less time and cost. (D) CR-39 is the most common titanium lenses due to their low weight. (E) sunglasses are used for fashion values.