Alonzo tries to run out of his classroom without permission and forcefully resists attempts to stop him. Behavioral assessment information leads to two hypotheses regarding Alonzo's behavior. The behavior analyst decides to conduct systematic manipulations to determine functional relationships. The MOST important reason to do this is to

Echoic behavior is controlled by a

A teacher's students were asking for individual assistance at a high rate when they were instructed to work independently using their textbooks and other resource material available in the classroom. The teacher posted a "No Questions" sign and systematically ignored the students' questions when the sign was up.
The rate of question-asking decreased to zero. Now the teacher simply puts up the sign whenever the students are to work independently and removes it when the students can ask questions. With respect to asking questions, the sign functions as:

The use of a withdrawal design is LEAST appropriate when:

What does this graph depict?