Answer : Option A

Explanation :

In MS-DOS, relocatable object files and load modules have extensions is .OBJ and .COM or .EXE, respectively.
.OBJ : OBJ is a geometry definition file format first developed by Wavefront Technologies for its Advanced Visualizer animation package. The file format is open and has been adopted by other 3D graphics application vendors.

.COM : The domain name com is a top-level domain in the Domain Name System of the Internet. Its name is derived from the word commercial, indicating its original intended purpose for domains registered by commercial organizations. Later, the domain opened for general purposes.

.EXE : EXE is a file extension for an executable file format. An executable is a file that contains a program - that is, a particular kind of file that is capable of being executed or run as a program in the computer. An executable file can be run by a program in Microsoft DOS or Windows through a command or a double click.