The correct option is C Declarative Sentence
Sentences are mainly divided into four types: declarative, imperative,
interrogative and exclamatory. Declarative sentences merely declare or
state something, imperative sentences express a command, an order or a
request, interrogative sentences intend to ask a question and
exclamatory sentences display extreme or sudden emotion. The given sentence states an action, that the speaker has booked tickets. This is characteristic of a declarative sentence, hence option B is correct. The sentence does not express a command or request; it does not even ask something or display any emotions. Hence options A, C and D are incorrect.