Which One of the Following Teaching Strategies Is the Clearest

Which one of the following teaching strategies is the clearest example of how a teacher might scaffold complex cognitive processes in instruction?

A) Give students index cards with the words YES and No,and have them use the cards to "vote" on answers to questions presented during classroom lectures.
B) Have students tutor younger children on subject matter they know very well.
C) Provide considerable guidance on problem-solving tasks early in the school year and gradually remove this guidance as students become more proficient.
D) Make sure students have mastered the basic facts and skills taught in one unit before proceeding to the next unit.