Complete the following sentence by choosing the correct option:

I am tired as _________ since 7 o'clock in the morning.

I have been working

The correct answer is Option (1) - I have been working

Present Perfect Continuous Tense:

• The sentence refers to an action that started in the past (at 7 o'clock in the morning) and continues up to the present. The present perfect continuous tense is used to describe such actions.
• "I have been working" correctly conveys this meaning.

I am tired as _I have been working________ since 7 o'clock in the morning.