*Question*
If rivers are what form canyons, then what are canyons formed by? Answer choices: - rocks - rainfall - rivers - mechanical force - calcite - silt - water - gravity
**Answer**
rivers

*Question*
If infection can cause an aneurysm, then what can cause an aneurysm? Answer choices: - smoking - infection - bacteria - viruses - Pollution - steroids - influenza - rays or beams
**Answer**
infection

*Question*
If cells are programmed to a limited number of divides, then cells are what to a limited number of divides? Answer choices: - increased - standardized - warm-blooded - critical organs - forced - programmed - white - fertile
**Answer**
programmed

*Question*
If sand and dust are formed by mechanical weathering, then what is a beach formed by? Answer choices: - movement of tectonic plates - heat change - mechanical weathering - By coral exoskeletons - seasonal changes - patch reefs - sedimentation - Nurseries of the ocean.
**Answer**
mechanical weathering