Answer: B
Correct answer: informed the members
Inform is a transitive verb and takes a direct object with no preposition: informed the members. It belongs to a group of verbs that are transitive in English but attract an unnecessary preposition in Indian usage: discuss, describe, emphasise, investigate, order, request, resemble, accompany, reach, enter, approach, obey, marry and inform. One does not discuss about a matter or reach at a station. What follows the object may of course take a preposition, and about is correct there: informed the members about the change, or informed the members of the change. The corresponding nouns do take prepositions - information about, a discussion about - which is precisely where the confusion originates.