Answer:
D. He should designate all the files in the shared folder as read-only.
Step-by-step explanation:
The steps Rony should take while using a peer-to-peer (P2P) network to prevent his original files from being overwritten by another P2P user is that He will make the file as read-only.
In making the file read-only, other users who have access to the shared folder can only read the file without modifying it's content.
By default, he is already the owner of the file, so option B is not the correct answer.
Also making the file executable give other users higher privilege, so option A is also not correct.