I've searched the net and I simply cannot find which is preferable--I, for one, think that IN TO is appropriate, but I can't explain to someone else WHY I chose to separate the words.
A. The correct word here is INTO. The difference between IN and INTO is that IN refers to something or someone who is already inside a particular place. INTO refers to someone on the outside coming in.
My sister came INTO the office.
My brother was already IN the office.