Directions (1-5) : Read the following passage carefully and answer the questions given below it in the context of the passage.

Controversy sometimes dogs the Nobel Prize, with critics pointing out more 'deserving' candidates who could have won it. But few people would grudge 2004 winners in Physics and Chemistry. Physicists David Gross, David Politzer and Frank Wilczek have been honoured for throwing light on the materials that build atoms, and the forces that hold them together. They worked out how and why quarks- elementary particles that nature uses to build the neutrons and protons in the nuclei of atoms- clump up in three- somes by 'painting' them in red, green or blue. This is not unlike having an electrical charge that is positive or negative, and whose combinations lend stability to the quark collections.

Question-3 : Neutrons are built by—