Answer:
dürfte
Step-by-step explanation:
- Although dürfte is indeed simple past, it's the 1st person singular/3rd person singular version of the verb in Konjuntiv II.
- Nevertheless, a helpful rule for remembering the simple past version of the three modal verbs with umlauts (dürfen, können, and mögen) is that the simple past versions of these verbs all lose their umlauts (durfte, konnte, mochte).