The Part of an Automobile That Has Been Most Closely

question 5

Short Answer

The part of an automobile that has been most closely regulated in an effort to make the air cleaner is the _____________________.

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Definitions:

Depression

In geology, a landform sunk below its surroundings, forming a low area which can be natural or man-made.

Valley

A low area between hills or mountains, typically with a river running through it.

Ridge

A long, narrow elevation of land, often formed by the continuous movement of the Earth's crust.

Ridges

Elevated geological features, typically linear, that can form through tectonic activities such as at mid-ocean ridges or due to erosional processes.