I will not beat around the bush; "alot" is not a word. Never has been. Don't use it. When was the last time you were tempted to write "alittle"? See. Doesn't work.
The correct answer is "b. My report needs a lot more data."
You mean "a lot," with a space between the two individual words, if you are talking about quantity. "I want to be paid a lot of money" is how you'd spell out your grammatically-correct requirement on the job application.
Or you might mean "allot" if you are discussing portion distribution: "The meeting chairperson allotted one donut and ten minutes speaking time to each attendee." Note that the double-L "allot" is a verb (AKA "action word," see Schoolhouse Rock for a refresher).
Here is a rather fun visual for remembering that "alot" doesn't mean "a lot."
I hope you learned a lot today!