A、The technical manager. B、The sales manager. C、The laboratory manager. D、The operation manager. C对话中提到“The Lab Manager supervis

Lisa: David, could you explain the company’s organization to me, as I find it a bit confusing?
David: Oh, yes, 1 understand. It does seem a bit complicated at first, but after you’ve been working here for a while, you’ll soon know who everyone is. Basically, there are two main offices in China, which are both controlled by the China Country Manager.
Lisa: Yes, I’ve got that. So, the Northeast Operation Manager...where is he based?
David: That’s me actually. My office is in Shanghai, but I have to travel a lot to Beijing and Tianjin, as we have customers there too.
Lisa: Okay. And for South China...that’s Guangzhon...you have an Operations Manager also?
David: Yes, that’s fight. So we both report to the Country Manager.
Lisa: Yes, I see.
David: Now, under me there’s a Technical Manager and a Sales Manager.
Lisa: Okay. And what is the Technical Manager responsible for?
David: Well, Quality Control. we have one person who does that and...er...he’s also responsible for the Laboratory Manager. The Lab Manager supervises the operators- they’re the ones who actually operate the machines.
Lisa: Mm...and what about the Sales Manager, who does he manage?
David: Well he heads the Sales Team. Each one of the sales people is responsible for selling in one area—er, one for Jiangsu, one for Zhejiang, and so on. And that’s really the Shanghai Team. Now, as you can see the Guangzhou Office is organized slightly differently.
Lisa: Yes, it must be a bigger office, isn’t it?
David: Yeah, that’s it...er...it’s a bit bigger, ’cause they cover Hong Kong too. So under the Operation Manager, there’s a Production Manager, a Lab Manager, and a Sales Manager.
Lisa: Right. So, the Production Manager...he’s er...or she?
David: He ... actually...you’ll meet Bill later today. He’s responsible for Quality Control...there are two people in Guangzhou doing that...and for the operations and the cleaners. He’s very strict actually; he supervises everyone very strictly.
Lisa: Oh, really?
David: Oh yeah, he’s very good. Quite a big team for the South of China. So, that’s it. Is that all you wanted to know for the moment?
Lisa: Yes, thank you. I’m sure I’ll find out more as I go along.
Question : Where is the base of the Northeast operations office?

Who supervises the operators?