Question

many people discover that attempts to bleach sunscreen marks off clothing produce vivid red stains instead of removing them. curious about this effect, chemists at durham university tested 11 commercial sunscreens with household bleach and found that only those containing the ultraviolet filter diethylaminohydroxybenzoyl hexyl benzoate (dhhb) generated the crimson hue. nuclear magnetic resonance experiments and computer simulations revealed that bleach converts dhhb into an unusually chlorinated product, via ipso - dichlorination (placing two chlorine atoms on the same position of an aromatic ring), that absorbs most visible wavelengths except red. the team then designed a modified, ipso - dichlorination - resistant version of dhhb that kept its uv - absorbing profile but barely changed color in the presence of bleach. taken together, this work suggests that ______
13 mark for review
which choice most logically completes the text?
a chemically informed redesign of uv filters like dhhb can yield sunscreens that withstand bleach without producing vivid red by - products, preserving effective photoprotection while greatly reducing the risk of unsightly, bleach - triggered staining on fabrics.
b the safest response to bleach - induced staining is for manufacturers to abandon robust uv filters altogether, accepting weaker sun protection so that no component of a sunscreen can ever react with laundry products to generate colored molecules.
c the mysterious red hue must result mainly from dyes in clothing rather than from sunscreen ingredients, so future stain - avoidance efforts should focus on reformulating textiles instead of altering the molecular structure of uv filters such as dhhb.
d typical laundry bleach is an ideal partner for sunscreen formulators, since its ability to convert dhhb into a strongly light - absorbing red compound can be exploited to create deliberately colored, chlorine - activated finishes on garments.

Explanation:

To solve this, we analyze each option:

• Option A: The team redesigned DHHB to be bleach - resistant while keeping UV - protection. So a chemically informed redesign of UV filters (like DHHB) to make sunscreens that withstand bleach (no red stains) while preserving photoprotection and reducing bleach - triggered staining makes sense. This aligns with the team's work of modifying DHHB.
• Option B: The team modified DHHB to keep UV - protection, so "abandon robust UV filters" and "weaker sun protection" go against their work. Eliminate B.
• Option C: The study shows the red hue comes from DHHB (not clothing dyes), so "result mainly from dyes in clothing" is wrong. Eliminate C.
• Option D: The problem is that bleach causes red stains on sunscreen - marked clothes, so bleach is not an "ideal partner" for sunscreen formulators. The team's work is to fix the bleach - DHHB interaction, not exploit it for colored finishes. Eliminate D.

Answer:

A. chemically informed redesign of UV filters like DHHB can yield sunscreens that withstand bleach without producing vivid red by - products, preserving effective photoprotection while greatly reducing the risk of unsightly, bleach - triggered staining on fabrics.