Sometimes the meaning of glowing water is ominous. Off
the Pacific Coast of North America, it may mean that the sea is
filled with a minute plant that contains a poison of strange
and terrible virulence. About four days after this minute
plant comes to alter the coastal plankton, some of the fishes
and shellfish in the vicinity become toxic. This is because in
their normal feeding, they have strained the poisonous
plankton out of the water.

5. In the context of the passage, the word virulence in line 4 means

A) strangeness
B) color
C) calamity
D) potency
E) powerful odor

(A) If "virulence" meant "strangeness," the segment would read "contains a poison of a strange and terrible strangeness" which would be redundant and not make sense. "Potency" means "power" or "strength." A "strange and terrible power" makes sense. Choice D is correct. See Reading Comprehension Strategies 1 and 5, p. 136 and 140, to practice with the strategy.

(B) What would a "terrible" color mean? "Potency" means "power" or "strength." A "strange and terrible power" makes sense. Choice D is correct. SeeReading Comprehension Strategies 1 and 5, p. 136 and 140, to practice with the strategy.

(C) A "calamity" is terrible in itself. So you wouldn't modify "calamity" with "terrible" and say "terrible calamity." "Potency" means "power" or "strength." A "strange and terrible power" makes sense. Choice D is correct. See Reading Comprehension Strategies 1 and 5, p. 136 and 140,to practice with the strategy.

(D) You are right. "Potency" means "power" or "strength." A "strange and terrible power" does make sense. SeeReading Comprehension Strategies 1 and 5, p. 136 and 140,to practice with the strategy.

(E) A "powerful odor" would not necessarily make the fish toxic. A strange and powerful poison would. "Potency" means "power" or "strength." A "strange and terrible power" makes sense. Choice D is correct. SeeReading Comprehension Strategies 1 and 5, p. 136 and 140, to practice with the strategy.