• Choice A is awkward

:thumbup: and poorly phrased: these has no plural noun to which it can refer, and
even should be placed immediately before to take calls, the phrase it modifies
• Choice B is best
• In C
the plural they does not agree with the singular company
even is misplaced [just as "even" is misplaced in option A]
and advise . . . that . . . they SHOULD is unidiomatic [because "advise" is used as a bossy verb, a context in which command subjunctive is required ]
• D has the plural companies [which is correct] but D retains the other flaws of C
• In E
who in place of that is an inappropriate pronoun for company ["who" is never used to refer to things, and always used to refer to people]
these does not agree with the singular offer, and
"is the refusal" should be "be to refuse"