This is a Constrained Distribution problem — distributing distinct objects into distinct containers with no container left empty. It's trickier than a standard Combinations question because the constraint forces you to think about partitioning first.
The common trap: jumping straight to 4^5 = 1,024 (assigning each candy to any of 4 jars freely) without applying the "no jar empty" constraint. That gives 1,024 — none of the answer choices — and sends students into a spiral.
Step 1: Figure out the only valid partition.
We have 5 candies going into 4 jars with no jar empty. The only way to distribute 5 distinct items into 4 non-empty groups is 2 + 1 + 1 + 1 (one jar gets 2 candies, the other three each get 1). There is no other valid partition — 3+1+1+0 leaves a jar empty, and 2+2+1+0 does too.
Step 2: Choose which 2 candies share a jar.
C(5, 2) = 10 ways
Step 3: Now we have 4 groups — one pair and three singles. Assign these 4 groups to the 4 distinct jars.
4! = 24 ways
Step 4: Multiply.
Total = 10 × 24 = 240
Answer: B (240)
The key insight is that with 5 items and 4 non-empty jars, the partition 2+1+1+1 is forced — there's only one structure to consider. Recognizing this immediately cuts the problem from "complex counting" to a clean two-step calculation.
Takeaway: In constrained distribution problems, always identify the valid partition(s) first — it tells you exactly how many cases to calculate and prevents over-counting.