Three of the Following Teachers Are Helping Their Students Solve

Three of the following teachers are helping their students solve problems more effectively? Which teacher probably is not?

A) When students struggle with arithmetic word problems, Mr.Azari gives them subtle hints about how to proceed.
B) Mr.Coleman presents many ill-defined problems in biology and asks students to make each one more specific and clear-cut.
C) Ms.Singh has students work on difficult problems in small, cooperative groups.
D) Ms.Abbott teaches students abstract principles of logic (e.g., "If all As are Bs and all Bs are Cs, then...") .