6.Read the passage:
The Great Barrier Reef is one of the most amazing ecosystems on the planet. Located off the coast of Australia, it is the world's largest coral reef system, stretching over 2,300 kilometers. The reef is home to an incredible array of marine life, including more than 1,500 species of fish, 600 species of coral, and many other creatures such as sharks, rays, and turtles. The reef's coral structure provides a habitat for these animals to live, feed, and breed. Unfortunately, the Great Barrier Reef is facing many threats, including climate change, pollution, and overfishing. Rising sea temperatures are causing the coral to bleach, which can be deadly to the coral and the animals that depend on it. Conservation efforts are underway to protect the reef and its inhabitants, but more needs to be done to ensure the long-term health of this incredible ecosystem.
What is the main idea of the passage about the Great Barrier Reef? (A)The Great Barrier Reef is an important ecosystem that is facing many threats.
(B)The Great Barrier Reef is the largest ecosystem in the world.
(C)The Great Barrier Reef is located off the coast of South America.
(D)The Great Barrier Reef is home to only a few species of fish.