Final answer:
The appropriate expression to fill in the blank is 'Qué rollo', which means 'What a bore'.
Step-by-step explanation:
The appropriate expression to fill in the blank in the sentence is B. Qué rollo. In English, this expression means 'What a bore'. So, the complete sentence would be 'No me gusta la clase de matemáticas. ¡Qué rollo!'. This expression is used to express one's lack of interest or dislike for a particular activity or situation.
Learn more about Expression for expressing dislike in Spanish