They are all correct. In your example, they all mean the same thing: a special low price, offered for a limited time or with specific conditions. "Discount" usually means just a simple price reduction. "The price of the hotel room is $129, but if you are over 65 years old, we offer a senior discount of 10%" "Deal" could mean something more complicated. "Come in to our car dealership, we are offering great deals." That is not saying "we will give everyone a 10% discount." It might mean "if you buy this model in this color, we will give you the deluxe sound system at no extra cost." A "deal" can also mean a complicated business negotiation. For example, "the two countries are trying to work out a trade deal." In that context, you could only use the word "deal."

Thank you guys very much for the help!

They all mean slightly different things but if you are using the sentence to describe a product or service being offered for a cheaper price than normal then any of these words can be used. Hope that helps. Alice

Yeah they all sound correct to me