Right Answer:
entradas…la taquilla
According to the context this is the right option. When you go to the movie theater you have to buy tickets (entradas) at the ticket office (taquilla) if you want to watch the movie.
Then, the complete sentence is:
Tenemos que comprar entradas en la taquilla para entrar en el cine.
We have to buy tickets at the ticket office to enter the movie theater
The options escenas (scenes), el teatro (the theater), filas (lines), la butaca (the seat), pantallas (screens) and el cine (the cinema or movie theater) do not match the context of the sentence
.
