Conjunction, Puncuation, and Maybe Writing Technique?

When writing research papers, it's a lot about answering why or how. I used to avoid complete sentences in stating reasons but I understand that complete sentences can be used as well.

The reasons (1), 2), 3)) are written in the form of complete sentences.

Ex1:

The reasons are 1) A is B; 2) C is A; and 3) D is B.

Ex2:

The reasons are 1) A is B, 2) C is A, and 3) D is B.

*The reasons are seperated by commas instead of colons.

Ex3:

The reasons are: 1) A is B; 2) C is A; and 3) D is B.

*A colon is added after "are."

Ex4:

The reasons are 1) A is B; 2) C is A; 3) D is B.

*Omited the "and" at the end.

Ex5:

The reasons are 1) A is B; 2) C is A; 3) D.

*The last reason is not a complete sentence while the other 2 reasons are.

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To give an example (just in case you find the whole lettering annoying):

1. The reasons are 1) the crime was already commited; 2) the offender repented about the crime; 3) the victim is still suffering due to the crime.

2. The reasons are 1) the crime was already commited; 2) the offender repented about the crime; 3) the victim is still suffering due to the crime.

3. The reasons are: 1) the crime was already commited; 2) the offender repented about the crime; 3) the victim is still suffering due to the crime.

4. The reasons are 1) the crime was already commited, 2) the offender repented about the crime, and 3) the victim is still suffering due to the crime.

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I would greatly appreciate if you have any links on this particular writing technique.

Are the above examples grammatically and punctuation wise correct?
If not, please explain why.

Thanks in advance.