白天植物光合作用从叶片气孔散失到大气中的气体是[ ]

A．二氧化碳

B．水蒸气

C．氧气

D．氮气

W: I need to talk to someone who knows Baltimore well. I’m told you lived there.
M: Oh, but I was really young at the time.
Q: What does the man mean().

A. He moved to Baltimore when he was young.

B. He can provide little useful information.

C. He will show the woman around Baltimore.

D. He will ask someone else to help the woman.