Question

low tail pipe ______ mean a vehicle is running efficiently, which helps to conserve energy.

a. testing
b. emissions
c. standards
d. regulations

Explanation:

• "Low tail pipe emissions" is a common phrase. Emissions refer to the substances (like gases) that come out of a vehicle's tail - pipe. If emissions are low, it can indicate efficient running (less wasteful combustion, for example) which conserves energy.
• Testing (a) is an action (like conducting a test on emissions), not what comes out of the tail - pipe.
• Standards (c) are like benchmarks (e.g., emission standards), not the actual substances from the tail - pipe.
• Regulations (d) are rules (e.g., emission regulations), not the physical output from the vehicle.

Answer:

B. Emissions