Match the Numbers to the Words That Goes in Each

Short Answer

Match the numbers to the words that goes in each box in comparing variable-outcome shaping and fixed-outcome shaping.
$$\begin{array} { | l | c | c | } \hline & \text { Fixed-outcome shaping } & \text { Variable-outcome shaping } \\\hline \text { \# of outcome sizes } & 1 & 2 \\\hline \begin{array} { l } \text { Regression to earlier } \\\text { levels }\end{array} & 3 & 4 \\\hline \text { Usual source of shaping } & 5 & 6 \\\hline\end{array}$$
-Number 5 is :
A)No reinforcers
B) Weaker reinforcers
C) Performance manager
D) Nature
E) One
F) Many