Final answer:
The correct verb to complete the sentence is 'conozcan'.
Step-by-step explanation:
The correct verb to complete the sentence is conozcan. In this sentence, the verb should agree with the subject 'tus amigos' which is in the third person plural form. The conjugation of the verb 'conocer' in the present subjunctive form for the third person plural is 'conozcan'. The sentence will be:
Yo dudo que tus amigos conozcan la cultura de mi país.
Learn more about conjugation of verbs in Spanish