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

Passage: Bacteria called cyanobacteria are very important. They are bluish green in color (see Figure below ) because they contain chlorophyll. They make food through photosynthesis and release oxygen into the air. These bacteria were probably responsible for adding oxygen to the air on early Earth. This changed the planet's atmosphere. It also changed the direction of evolution. Ancient cyanobacteria also may have evolved into the chloroplasts of plant cells. Answer: chlorophyll
Cyanobacteria are bluish green in color because they contain what?

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
How many stomach compartments do ruminants have?

Passage: The rocks in this photo of the Grand Canyon are all sedimentary. Hard rocks that are resistant to weathering form cliffs. Softer rocks that weather more easily form slopes. Answer: cliffs
In places like the grand canyon, hard rocks that are resistant to weathering form what, while softer rocks that weather more easily form slopes?