Coral reefs face a serious threat from rising ocean temperatures, which cause the symbiotic algae living in coral tissue to be expelled — a process called bleaching. To address this, marine biologists have begun cultivating heat-resistant coral strains in laboratories. These strains are then transplanted into damaged reefs, where they appear to survive temperature spikes that would kill ordinary corals.
Which choice best describes the overall structure of the text?
- A
It compares two competing theories about coral evolution.
- Bcheck_circle
It presents a problem and then describes a proposed solution.
- C
It defines a term and provides three examples.
- D
It traces the historical discovery of coral reefs.
Explanation
The text begins with the bleaching problem, then describes the lab-cultivation solution. B fits the structure exactly.