.... Lehrer heisst Birkel.
B
Correct answer
Explanation
This German possessive pronoun question asks 'Our teacher's name is Birkel.' 'Unser' means 'our' in the nominative case with masculine noun 'Lehrer'. 'Euer' is informal plural 'your', 'Ihr' is formal 'your', and 'Dein' is informal singular 'your'. Only 'Unser' correctly means 'our'.