Choose the correct option. My dad _______ a new book in the garden now.

The correct option is "isn't reading". Explanation: The sentence requires the present continuous tense, as indicated by the word "now". The present continuous tense is formed with the present tense of the verb 'to be' (am, is, are) followed by the verb ending in '-ing'. The subject is 'My dad' which is singular, so the correct form of 'to be' is 'is'. Therefore, the correct answer is 'isn't reading'. The other options are incorrect for the following reasons: * "isn't read": This form is passive and doesn't fit the meaning of the sentence. * "doesn't read": This is in the simple present tense and doesn't fit the current action described by "now". * "aren't reading": This is the present continuous form, but with 'are' that doesn't agree with the singular subject ('My dad'). Thus, the correct sentence is: "My dad isn't reading a new book in the garden now."