Answer:
Marissa trashed the doughnuts because they were totally gross- very informal.
Marissa threw the doughnuts in the trash can because she knew they had exceeded their expiration date- informal.
Marissa understood the hazards of eating expired doughnuts, and with very little hesitation she deposited the aforementioned eatables into the garbage receptacle- formal.
Step-by-step explanation:
1. In the first sentence, the use of the words "trashed" and "gross" are just everyday simple language used between known people. So, this type of sentence is very informal.
2. The second sentence is an informal sentence in that it used the simple yet not too simple words which cannot be really used in a formal setting/ conversation.
3. The third sentence is a formal sentence for the words used in it that can be used in a formal conversation. The words like "hazards", "deposited', "aforementioned eatables", "garbage receptacle" all suggest a formal tone, rather than the informal and easy language.