Which of the following is true about the two charged vanes that produce electric field in Paramagnetic oxygen analyzer?

• A. Both the vanes should be at higher potential than the test body
• B. Both the vanes should have the same potential as the test body
• C. One vane should be at higher potential than the test body and the other vane should be at lower potential
• D. Both the vanes should be at lower potential than the test body