Both a and b are correct depending on context.

I can't click on just ONE because TWO are correct. Am I supposed to click the one that is WRONG? I'll try clicking on the wrong one to see what happens.

Is Coming and Will Come are both fine.

Topic: future tense Both a and b are correct, it depends on the tense been used.

No. Clicking the one wrong one tells me I am wrong (perhaps obviously!). But I don't seem to be able to click on the two that are right. How do you do this quiz question?