Explanation:

The correct answer is option C: "on / in".

When we talk about the location of an object, we use prepositions to indicate where it is in relation to another object. In this case, we are talking about the location of the paper in relation to the floor and the wastebasket.

- On / In: We use the preposition "on" to indicate that something is physically touching or resting on a surface. In this sentence, the paper is physically touching the floor, so we say "on the floor". We use the preposition "in" to indicate that something is inside or contained within a container or space. In this sentence, we want the paper to be inside the wastebasket, so we say "in the wastebasket".

- At / Into: We use the preposition "at" to indicate a specific location or position. In this sentence, using "at" would not accurately describe the relationship between the paper and the floor or wastebasket. We use the preposition "into" to indicate movement or direction towards the inside of something. In this sentence, we are not talking about the movement of the paper into the wastebasket, but rather the paper being in the wastebasket.

- Over / At: We use the preposition "over" to indicate that something is positioned above or covering something else. In this sentence, we are not talking about the paper being positioned above the wastebasket, but rather inside it. We use the preposition "at" to indicate a specific location or position, which does not accurately describe the relationship between the paper and the floor or wastebasket in this sentence.

Therefore, the correct prepositions to complete the sentence are "on" for the paper's position on the floor and "in" for the paper's position in the wastebasket.