Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Plasma cells are activated B cells that secrete antibodies. Antibodies are large, Y-shaped proteins that recognize and bind to antigens. Plasma cells are like antibody factories, producing many copies of a single type of antibody. The antibodies travel throughout the body in blood and lymph. Each antibody binds to just one kind of antigen. When it does, it forms an antigen-antibody complex (see Figure below ). The complex flags the antigen-bearing cell for destruction by phagocytosis . Answer: antibodies
[EX A]: What do you call large, y-shaped proteins that recognize and bind to antigens?

[EX Q]: Passage: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. Only with fluorine does oxygen form compounds in positive oxidation states. Answer: positive oxidation states
[EX A]: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. only with fluorine does oxygen form compounds in this?

[EX Q]: Passage: To measure very small masses, scientists use electronic balances, like the one in the Figure below . This type of balance also makes it easier to make accurate measurements because mass is shown as a digital readout. In the picture, the balance is being used to measure the mass of a white powder on a plastic weighing tray. The mass of the tray alone would have to be measured first and then subtracted from the mass of the tray and powder together. The difference between the two masses is the mass of the powder alone. Answer: electronic balance
[EX A]:
What instrument, with a digital readout, is used by scientists to measure very small masses?