The correct option is C I thought I was seeing a ghost!
The correct answer is Option C. Diary entry generally uses language to express one's personal experiences. Options A and D are incorrect as it is seen that it has been written for someone else using 'he', a third person pronoun instead of 'I', a first person pronoun. Option B is incorrect as the sentence is in future tense and generally diary is a record for events that have already occurred.