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

Q: Passage: Lasers Most light emitted by atoms is polychromaticcontaining more than one wavelength. In contrast, lasers (from light amplification by stimulated emission of radiation) emitmonochromatic light a single wavelength only. Lasers have many applications in fiber-optic telecommunications, the reading and recording of compact discs (CDs) and digital video discs (DVDs), steel cutting, and supermarket checkout scanners. Laser beams are generated by the same general phenomenon that gives rise to emission spectra, with one difference: only a single excited state is produced, which in principle results in only a single frequency of emitted light. In practice, however, inexpensive commercial lasers actually emit light with a very narrow range of wavelengths. How a CD player uses a laser to read a CD. Inside a CD is a flat, light-reflecting layer called "land. " On the land are many "pits" recorded in a spiral-shaped track. (From the laser's point of view, pits are actually the "bumps" shown here because the master disc with pits is duplicated negatively, turning the pits into bumps. ) Pits have the same light-reflecting surface as land, but there are differences in the frequencies of the reflected light in the pit and the land, making light reflected by pits relatively dark compared with light reflected by land. Answer: wavelength

A: Light emitted by atoms is polychromaticcontaining more than one of these?
****
Q: Passage: Bone marrow is a soft connective tissue that produces blood cells. It is found inside the pores of spongy bone. Answer: bone marrow

A: What is found inside the pores of spongy bone?
****
Q: Passage: To help digest the large amount of plant material, the stomach of the ruminants is a multi-chambered organ, as illustrated in Figure 34.8. The four compartments of the stomach are called the rumen, reticulum, omasum, and abomasum. These chambers contain many microbes that break down cellulose and ferment ingested food. The abomasum is the "true" stomach and is the equivalent of the monogastric stomach chamber where gastric juices are secreted. The four-compartment gastric chamber provides larger space and the microbial support necessary to digest plant material in ruminants. The fermentation process produces large amounts of gas in the stomach chamber, which must be eliminated. As in other animals, the small intestine plays an important role in nutrient absorption, and the large intestine helps in the elimination of waste. Answer: four

A:
How many stomach compartments do ruminants have?
****