Algicidal treatment?

• A. A method of cleaning discolored shingles with a bleach mixture to lighten discoloration caused by algae formation
• B. A test to measure algae quantity
• C. Algicidal treatment
• D. A coating that seals algae

Answer: (C)

The main idea is recognizing what an algicidal treatment is: a chemical product designed to actively kill algae on roofing surfaces and help prevent it from coming back. This is the term that directly describes the treatment used to remove existing algae and reduce future growth on shingles. It’s more specific than just cleaning with a bleach mix, which may lighten stains but doesn’t inherently kill the algae or prevent regrowth. It’s also not a test to measure algae, which is diagnostic, nor a coating that seals the algae, which doesn’t address live growth. So naming the treatment itself—the algicidal product used to kill algae on the roof—best fits what’s being asked.