The attitude of a text toward the subject being discussed is called tone.
Option D.
Explanation:
Tone is the author’s attitude towards any subject or characters or audience. Tone is usually delivered with the help of different choice of words.
Every written piece consist of a theme and a message which is being conveyed by using tone. There are many examples of tone, it can either be funny or ironic or sad or formal or anything that the writer wants to convey. It is only because of tone that the writer is able to convey his viewpoints.