Our geography teacher is ( ).

A .interesting
interesting是形容事物 但是interested是be interested in doing 或是take an interest in 例如
She is a interesting girl.
She is interested in singing,
She takes an interest in singing.
所以Our geography teacher is ( interesting ).
意思是我们的地理老师很有趣 等同于She(He) is interesting 她（他）很有趣