Official Solution:In reference to the current popularity of electronic mail, postal services frequently expressed anxiety that their prospects for remaining profitable are being limited by their antiquated business model.
A. In reference to the current popularity of electronic mail, postal services frequently expressed anxiety that
B. Referring to the current popularity of electronic mail, postal services frequently expressed anxiety about
C. When referring to the current popularity of electronic mail, postal services frequently express anxiety about
D. With reference to the current popularity of electronic mail, postal services frequently expressed anxiety about
E. Referring to the current popularity of electronic mail, postal services frequently express anxiety that
The original sentence has a verb tense problem.
Expressed is in the past tense and
are is in the present tense. The phrase
current popularity in the first part of the sentence as well as the verb
are in the non-underlined portion both suggest that we should change
expressed to the present tense.
This eliminates choices A, B, and D. Choice C is incorrect because, although it fixes the tense problem, it also incorrectly employs the preposition
about to introduce the noun clause describing the subject of the postal services' anxiety. Choice E properly uses
that instead of
about, and puts
express in the present tense.
Answer: E
Looking at C, does that mean , a preposition cannot introduce a noun clause, and that a Noun clause has to be introduced by a THAT ?