Jessica is a forensic investigator in a case of corporate espionage. An employee was found with a USB stick containing confidential information without authorization.

Before calling her, the IT Manager plugged the USB stick on their computer to verify the kind of information the employee had access to$,$ so some files were opened.

Why this action could have affected Jessica's investigation?

a$.$ The content of files could have been modified by the IT Manager

b$.$ The timestamp of files would be modified after the IT Manager accessed them

c$.$ The files hashes would not be the same after they have been accessed

d$.$ All of the others