Answer:
C. Declarative.
Step-by-step explanation:
A declarative sentence is one that simply states or declares an opinion. In other words, a declarative sentence is one that expresses a statement or an opinion.
The given sentence "I wake up by eight every day" is a declarative sentence. It expresses the simple statement or a declaration of the speaker that he/she wakes up by 8 every day.
It is not an exclamatory sentence as it doesn't exclaim anything nor does it contain the exclamatory mark (!).
Again, it is not an optative sentence as it doesn't express a desire or an opinion.
Also, it is not an imperative sentence as it does not demand or express a command.
Thus, the correct answer is option C.