def offer_simple(pool, answer, rationale, student_id, options):
existing = pool.setdefault(answer, {})<EOL>if len(existing) >= get_max_size(pool, len(options), POOL_ITEM_LENGTH_SIMPLE):<EOL><INDENT>student_id_to_remove = random.choice(existing.keys())<EOL>del existing[student_id_to_remove]<EOL><DEDENT>existing[student_id] = {}<EOL>pool[answer] = existing<EOL>
The simple selection algorithm.

This algorithm randomly select an answer from the pool to discard and add the new one when the pool reaches
the limit