Choose the appropriate option to fill in the blank:
A: Can we meet tomorrow afternoon?
B: Not in the afternoon. ___________ (I / work)
A) I’ve worked
B) I’d work
C) I’ll be working
D) I’ll have worked

Hint: Future continuous tense is also known as future progressive tense and this tense tells about something to happen in future and it is formed using the root verb + ing.

Complete answer:
Option A) I’ve worked – is an incorrect answer because ‘I’ve worked’ is in the present perfect tense. The meaning of ‘I’ve worked’ means that the work began at some point of time in the past and worked till the present. Thus, the use of this option is grammatically incorrect and makes the sentence incorrect.

Option B) I’d work – is an incorrect answer because ‘I’d work’ shows that something is stretching from the past and continues till present. And the sentence is in future continuous tense that A is asking about tomorrow, so, the use of ‘I’d work’ is appropriate here in the blank. Thus, this is an incorrect answer.

Option C) I’ll be working – is the correct answer because ‘I’ll be working’ means B will be busy tomorrow or unable to meet. So, this is also IN the future continuous tense and the use of this option here in the blank is grammatically correct. Thus, this is the correct answer.

Option D) I’ll have worked – is an incorrect answer because ‘I’ll have worked’ means I have already done with the work and this is grammatically incorrect in the blank. So, this is an incorrect answer.

Hence the correct answer is option ‘C’.

Note: In this particular question, future continuous tense is used to fill the blank and this tense is used to indicate an ongoing action at the specified time. Here the verb indicates the same. The syntax of future perfect continuous tense is: will/shall + be + verb (ing). Therefore, the correct option is C as compared to any other option.