Gretchen has been trying to teach glen, a preschooler, to pull up his pants by himself after using the toilet. she has been using a shaping model. she began by reinforcing him with an animal cracker for bending over and touching his waistband. he is now doing that consistently. next, she wants him to start pulling his pants a little bit. however, she has become very frustrated because glen continues to simply touch his pants rather than pull a bit. typically, a. glen has been allowed to bring an elmo doll into the bathroom with him when he uses the toilet. (earlier, elmo was used as a reinforcer for using the toilet.) b. glen sits elmo on a little potty chair in the bathroom while he uses the toilet. c. gretchen notices that the entire time d. glen is in the bathroom, he looks at elmo, talks to him, and sings sesame street songs. how should gretchen use this information?