"could not read block" error message

I have a perl script that's worked flawlessly for years to extract data from a PostgreSQL database and write the data
toa text file once a day.  The script is now terminating abnormally with this message: 

     DBD::Pg::db selectall_arrayref failed: ERROR:
     could not read block 53044 of relation "news":
     Input/output error at {script name} line 93.

The FreeBSD box hosting PostgreSQL shows this recurring message in its /var/log/messages file:

     postgres[18215]: [52-1] ERROR:  could not read block 53044 of relation "{xyz}": Input/output error

Are these error messages pointing to:

     (A) a physical defect on the hard drive;

     (B) something that's gone haywire inside the database; or

     (C) something else?