What is meant by a gateway substance? what is one example of a gateway substance what is wrong with assuming that use of a gateway substance causes increased use of other substances?

Gateway substance on regular usage, make an individual habitual usage of same or more harmful drugs

Explanation:

Any drug which has the capabilities of  becoming a mode of drug addiction for reuse again and again on usage for a short time period, then such drugs are called gateway substance.

Some common examples of gateway substance are alcohol, marijuana, nicotine. cocaine, heroin etc.

The gate way substance increase chances of an individual to take other drugs as it reduces the decision making capabilities of an individual

There are high chances that use of gateway substance can lead to dependence on more dangerous, addicting substances

ocean expansion, global warming is melting icebergs and causing water levels to rise.

the answer is b: 1.4 km/hr