What do coal and cubicle mean?

[Estela]

English Grammar Tests, Elementary Level

ESL/EFL Test #244 "Non-Count and Count Nouns (3)", question 4

......... is a valuable resource and is a fossil fuel. This is a non-count noun.

(a) Bottles
(b) Towels
(c) Coal
(d) Cubicle

English Grammar Tests, Elementary Level

ESL/EFL Test #244 "Non-Count and Count Nouns (3)", answer 4

Coal is a valuable resource and is a fossil fuel. This is a non-count noun.

Correct answer: (c) Coal
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WHAT DO COAL AND CUBICLE MEAN?

[HelloJordan]

Coal looks like a small black rock, it's used for fuel.
This is what it looks like --> http://cleantechnica.com/files/2008/04/coal_hands.jpg
A cubicle is a small square area that people use as their office.
This is what cubicles look like --> http://www.foundation3d.com/gallery/data/511/FISK-imaging-Cubicles.jpg