Why does the code raise a KeyError when accessing player['Name'] instead of player['name']?

Python dictionaries are case‑sensitive, so the key 'Name' is different from 'name'. In the provided data the dictionary uses the key 'name', but the code attempts to access 'Name', which does not exist, causing a KeyError. The fix is to use the correct key: player['name']. Consistency in key naming is essential; if you need to support both cases, you could normalize keys or use a case‑insensitive mapping. The corrected code appends the player dictionary with the proper key: groups['Under 30'].append({'name': player['name'], 'age': player['age'], 'reward': player['reward']}). This resolves the error and ensures the data is stored correctly.