Step 1: Understand the task.
We select the qualities a good facilitator needs from $J, K, L, M$.
Step 2: Check Creating activities (J).
Designing engaging activities drives active learning, so J belongs.
Step 3: Check Discriminatory behaviour (K).
Discrimination harms children and is never a facilitator quality, so K is rejected.
Step 4: Check Recognising mental ability (L).
Knowing a child's level lets the teacher guide appropriately, so L belongs.
Step 5: Check Subject knowledge (M).
Sound knowledge of the subject is needed to guide learning, so M belongs.
Step 6: Combine the valid qualities.
\[ J + L + M = \text{facilitator set},\quad K = \text{rejected} \]
Step 7: Choose the option.
J, L and M is option C.
\[ \boxed{\text{C. J, L and M}} \]