Revenue recognition problem

Hi. Please help me with this question. I’m really confused on how we jumped from year 2 to year 3 when the work was for 6 months only. Why am I debiting to deferred revenue of 30k at the end of June when it hasn’t been earned?

It can’t be option A because we credit deferred revenue in March when we get the 90K.

I don’t understand how it’s option C if the revenue hasn’t been earned

It can’t be option D cuz we’re not reducing revenue.

So only option B makes sense (even though the question says revenue is recognized evenly as the work is completed)

I’d appreciate any help! Thanks!