501 Critical Reading Questions

a
,
b
, and 
c
are distracters that might be chosen if not reading care-
fully. Choice 
e
, 
preparation,
is too vague.
387.
b.
Lines 30–32 clearly state that dentinal tubules 
are micro-canals
that radiate outward through the dentine from the pulp cavity to the
exterior cementum border.
388.
c.
In the passage, the substances in choices 
a
,
b
,
d
, and 
e
are all
described as organic substances. Therefore, choice 
c
, an inor-
ganic substance, is correct.
389.
a.
Lines 55–58 identify how natural ivory can be authenticated.
390.
c.
According to the fifth paragraph of the passage, enamel is the
hardest animal tissue (animal tissue, by nature, is a living thing,
and thus organic), ameloblasts help form it, and it has a pris-
matic structure (choices