TOPIC: Confusion about Resource leveling and Critical Chain method

As per PMBOK
Resource levelling is used when shared or critical resources are only available at certain times or in limited quantities or over allocated
Critical Chain method is used to account for limited resources and project uncertainties

In Mock exam 7, a question asked is which tool should we use when we need to prepare schedule based on limited resources.

if Answer is Critical Chain Method then when resource levelling can be used for resource limitation as mentioned above in PMBOK ?

what am I missing ?