A、San Francisco. B、Forest fires. C、Redwood trees. D、Survival skills. CWhat is the main subject of this conversation?

M: Have you ever visited a redwood forest?
W: Redwood? No, I’ve never seen a redwood tree, is it red?
M: Yes, its bark is kind of red. I recently had a chance to go to the Mill National Park, north of San Francisco. You can’t imagine how big they are.
W: Yeah, how big?
M: The coast redwoods are the tallest living things. Some are more than three hundred and fifty feet high. But none of the trees at Mill is that high. You have to go further north in California to see the tallest trees.
W: You said that Mill is near San Francisco? I used to think it must be quite a tourist attraction.
M: Yes, it’s less than an hour’s drive away, so it’s easy to get to.
W: I’ve heard that many redwood trees are thousands of years old. Are the ones in Mill that old?
M: The oldest documented age for a coast redwood is more than two thousand years. The trees at Mill are 400 to 800 years old.
W: Why have they survived so long?
M: They have remarkable resistance to forest fires. Their tough, thick bark protects the trees during a fire. The coast redwoods also like a damp, foggy climate.
W: Then since Mill is near foggy San Francisco, it must be ideal for the trees’ survival.
M: Have you ever visited a redwood forest?
W: Redwood? No, I’ve never seen a redwood tree, is it red?
M: Yes, its bark is kind of red. I recently had a chance to go to the Mill National Park, north of San Francisco. You can’t imagine how big they are.
W: Yeah, how big?
M: The coast redwoods are the tallest living things. Some are more than three hundred and fifty feet high. But none of the trees at Mill is that high. You have to go further north in California to see the tallest trees.
W: You said that Mill is near San Francisco? I used to think it must be quite a tourist attraction.
M: Yes, it’s less than an hour’s drive away, so it’s easy to get to.
W: I’ve heard that many redwood trees are thousands of years old. Are the ones in Mill that old?
M: The oldest documented age for a coast redwood is more than two thousand years. The trees at Mill are 400 to 800 years old.
W: Why have they survived so long?
M: They have remarkable resistance to forest fires. Their tough, thick bark protects the trees during a fire. The coast redwoods also like a damp, foggy climate.
W: Then since Mill is near foggy San Francisco, it must be ideal for the trees’ survival.
M: Yes, you must go there and see them; It’s wonderful; it’s the miracle of life.
W: I can’t wait.