Which of the following is an example of a quantitative observation? A. The surface of Mars is rocky
B. Sulfur smells similar to rotten eggs.
C Mercury is silver and shiny.
D. The plant is 20 centimeters tall.
PLEASE HELP , it’s a quiz question and it’s past due date

Waste water from industries and domestic sources can be treated by chlorination or ultraviolet radiation. there are pros and cons to using either chlorine or uv radiation to kill harmful microorganisms. what is one reason chlorination would be preferred over ultraviolet radiation? a) chlorine only eliminates visible impurities and is ineffective against microorganisms. b) chlorine not only kills bacteria but provides a residual effect on returning microorganisms. c) uv radiation can be used only to treat drinking water and is ineffective in treating waste water. d) ultraviolet radiation is more effective