Question

rare earths are a collection of 17 similar metals with special properties. they have many uses in fields like electronics, lasers, and glasswork. the term rare is somewhat misleading, as these elements are not necessarily rare in the sense of being scarce; one rare element, cerium, is about as abundant in earths crust as copper is. however, rare earths tend to be very widely dispersed, and only rarely appear in high enough concentrations to be economically mined. as a result, there are relatively few active rare earth mines in the world, in countries as diverse as russia, china, brazil, burundi, myanmar, australia, india, thailand, malaysia, and the united states.
according to the text, rare earths are so called because:
a they do not exist in large quantities on earth.
b the discoverers of rare earths wanted to mislead people.
c they are seldom used in industrial processes.
d there are few sites where they are mined.

Explanation:

To solve this, we analyze each option:

• Option A: The text says cerium is about as abundant as copper, so they do exist in large quantities on Earth. Eliminate A.
• Option B: The text doesn't mention anything about the discoverers wanting to mislead. Eliminate B.
• Option C: The text states they have many uses in fields like electronics, so they are used in industrial processes. Eliminate C.
• Option D: The text says "there are relatively few active rare earth mines in the world" and lists few countries with mines, meaning there are few sites where they are mined. This matches.

Answer:

D. there are few sites where they are mined.