The correct answer is C. has been reading.
The sentence is in the present perfect continuous tense, which is used to talk about an action that started in the past and continues up to the present. In this case, Bali has been reading the book since January last, which means that she started reading it in January and is still reading it now.
The other options are incorrect because they do not express the continuous aspect of the action. Option A, is reading, is in the present continuous tense, which is used to talk about an action that is happening right now. Option B, reads, is in the simple present tense, which is used to talk about an action that happens regularly or habitually. Option D, read, is in the simple past tense, which is used to talk about an action that happened at a specific time in the past.
Here are some examples of how the present perfect continuous tense can be used:
- I have been working on this project for two weeks.
- We have been waiting for you for an hour.
- The baby has been crying for ten minutes.
- They have been playing football since morning.