How has the invention of the personal computer helped people the most? OPTIONS:
- by replacing paper
- by reducing pollution
- by improving transportation
- by increasing communication
A: by increasing communication

Which action is an example of good water management? OPTIONS:
- letting faucets drip
- watering the grass every day
- turning off the faucet when brushing teeth
- running the dishwasher when it is not full
A: turning off the faucet when brushing teeth

Which of these is a safe practice in a laboratory investigation when working with chemicals? OPTIONS:
- pouring unused chemicals down the sink
- mixing leftover chemicals in one container
- wearing safety goggles when working with chemicals
- returning unused chemicals to the original container
A: wearing safety goggles when working with chemicals

How is the theory of plate tectonics different from a hypothesis regarding a certain aspect of plate movement? OPTIONS:
- The theory addresses an Earth-science topic.
- The theory may change if new evidence emerges.
- The theory explains a number of related observations.
- The theory can be evaluated by a single-variable experiment.
A:
The theory explains a number of related observations.