An experiment designs their experiment  so that a reinforcer is  delivered after a subject presses a bar  in Skinner box. to maximize  conditioning , which delay presses a  bar in a Skinner box. to maximize  conditioning which delay interval ( between the response and the  delivery of the (reinforcer) should be used /
 a) 1 second
 b) 2 second
 c) 4 second 
 d) 8 second