Final answer:
The correct command to compile a program called readit is gcc -o readit readit.c.
Step-by-step explanation:
The correct command to compile a program called readit is option 1) gcc -o readit readit.c.
gcc is the GNU Compiler Collection, a popular compiler for the C language. The -o flag is used to specify the output file name, which in this case is readit. The readit.c argument specifies the source code file to be compiled.