Critical Reasoning

Carnigan International Airport was once the busiest airport in the
region, but two major airlines have relocated to nearby airports,
reducing the number of ‡ights in and out of Carnigan by more than
half. The gates at Carnigan were built more than thirty years ago
and cannot accommodate the largest modern aircraft. In an e¤ort
to bring in more business, Carnigan o¢ cials plan to build dozens
of gates to accommodate modern aircraft and o¤er reduced-rate
leases to airlines willing to make long-term commitments.

Which of the following, if true, most threatens the plan’s likelihood
of success?
(A) Most of the airlines operating out of nearby airports
have long-term leases on gates at the other airports.
(B) The existing gates at Carnigan rent at rates that are, on
average, much lower than the proposed rates for the
new gates to be built there.
(C) Because of highway congestion and changing
development patterns that make Carnigan inconvenient
to access, airline customers prefer to depart from other
airports.
(D) Of the 18 airlines that serve Carnigan or nearby airports,
none serve more than one airport in the area.
(E) If the proposed addition is completed, Carnigan will be
the largest airport, as measured both by gates and
square footage, in the region

i was confused between B and C
I then decided on B as C introduces extra information about customers of the airport which was not there in original question

My question is on what parameters you decide that this is the scope or boundry and information provided in answer is outside scope