Which of the following is the best example of an abiotic factor limiting population size? a) the amount of aquatic plants eaten by snails in a pond b) the number of dead standing trees available as nesting sites for downy woodpeckers c) the spread of deadly human flu virus from one person to another by touching and sneezing d) the frequency of rainfall needed for the germination of desert plant seeds

1. seamount a raised footwall block between normal fault creates this 2. syncline break between rocks where a hanging wall rises relative to a footwall 3. hot spring on rolling hills, this a dip between hills 4. volcanic neck created when a block with hanging walls slips down between normal faults 5. caldera underwater volcano that never reaches above sea level 6. horst natural hot water on earth's surface containing many minerals 7. graben underwater volcano whose top is eroded flat by waves 8. crater less than a mile in diameter; looks like a bowl at the top of a volcano 9. guyot magma that filled the central vent that remains after the volcano has eroded 10. reverse fault over 1 mile in diameter; looks like a bowl over a volcano