(A) over is not needed in the sentence.

They were planning to have the picnic at Tiara’s house.

I’m not really a grammar whiz but, I’d have to go with D a preposition needs an object I think which is a noun that is not the subject of the sentence (or so Mrs Gerbig my 6th grade teacher told me many years ago…I wonder if she is still alive…) looking at the sentences, only D seems to have a noun as an object of “but” that is “work” also, note that the first three all have “but” after a comma, sort of connecting two separate parts of the sentence i think this makes the word “but” a conjunction, or maybe thats not the right word but some kind of “joining” word anyway, I’m voting for D the others are all the same so it can’t be them anyway

My answer is A.

B (have) is not a preposition. C and D are both needed in the sentence.

The sentence would read fine if you took out “over”: They were planning to have a picnic at Tiara’s house.

It’s A. A preposition is a word that shows direction or placement. “Over at” is a double use of prepositions and not necessary. Since “over Tiara’s house” wouldn’t make sense, it should be “at Tiara’s house” making “over” inappropriate.

it’s A over It’s not necessary to make the sentence complete

MC you need to settle down a little bit. Most questions have a trick answer in them(have being a preposition). Have is also not a noun. Haves is but not have. Slow your roll buddy.

“They were planning to have the picnic at Tiara’s house.” is the correct way to word this sentence.

NONE!

Have isn’t a preposition????? Have is either a noun or verb.

The preposition over isn’t necessary, but it certainly isn’t inappropriate.

over

(A) over.