Which of the Following Better Explains 'Gatekeepers

Which of the following better explains 'Gatekeepers'? 

A)  Those who control the flow of information from the supplier towards the other members of the Decision Making Unit (DMU) . 
B)  Those who control access to the organizations' property. 
C)  Those who can influence the media. 
D)  Those suppliers that meet the buyer's prequalification criteria and that will be requested to submit a first proposal.