Which of the following is/are essential features of a concept map in mathematics?
A. It represents a conceptual analysis of a concept using contributory sub-concepts.
B. They are directional, with arrows showing which concepts are prerequisite for which others.
C. They cannot be used for diagnostic purposes to identify difficulties in learning a particular concept.
D. The cannot be used frequently as they are very time consuming.
Choose the correct option.

Correct option is B

Concept maps are visual representations of concepts and their relationships. They can be used to represent a conceptual analysis of a concept using contributory sub-concepts, and they are directional, with arrows showing which concepts are prerequisite for which others.
Therefore, the correct answer is (b).