Final answer:
The correct adjective ending is 'en' in German.
Step-by-step explanation:
In German, the correct adjective ending in this sentence is en. So, the sentence should be 'Sie mag die roten Tasche.' The adjective ending changes based on the gender, case, and number of the noun it describes. In this case, 'rote' is used because 'Tasche' is a feminine noun in the accusative case.
Learn more about Adjective endings in German