Which of the following describe understanding level teaching ?A. Systematic, step by step presentation to promote retention of facts presentedB. Giving a large number of positive and negative examples to explain conceptsC. Insisting on effective storage of informationD. Helping to promote seeing of relationships among factsE. Critical sifting of facts and informationChoose the correct answer from the options given below:

• A. A and B only
• B. B and C only
• C. C and D only
• D. B and D only