Answer:
first drop down:
a. mass
second drop down:
b. weight
third drop down:
a. strength of gravity increases
fourth drop down:
b. weight decreases
Answer: B
Explanation: By most estimates, catalytic converters fitted inside the exhaust pipe of a gasoline-operated car convert over 90% of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) from the engine into less harmful carbon dioxide (CO2), nitrogen and water vapour.