What does the linux/unix command touch do? O a. Changes the name of the file O b. Modifies the contents of a file O c. Creates an empty file or updates the access and modification times of files O d. Removes a file what is an alternative to backquotes (as in blah='wc - hello.c) in bash. O a. The dollar-parenthesis notation (as in blah=$(wc - hello.c)) O b. Single quotes (as in blah='wc -- hello.c') . The dollar notation (as in blah=$wc - hello.c) Od Double quotes (as in blah="wc-c hello.c")