The teacher explained the theory clearly

Mark the letter A, B, C, or D to indicate the sentence that best combines each pair of sentences in the following questions.

The teacher explained the theory clearly. However, the students found it hard to understand it.

• A. Although the teaching theory was clear, there was a real challenge to the students.
• B. Despite the teacher's clear explanation of the theory, students had difficulty understanding it.
• C. In spite of explaining the theory clearly, students themselves found it hard to understand it.
• D. Though explained clearly, the theory of teaching was difficult to students.