Given the following part of a script: What is the meaning of $1?

Given the following part of a script:

if [ -f $1 ]; then
   echo “I am here”
fi

What is the meaning of $1?

• It is a special variable that indicates the exit code of the command before it
• It is the first argument passed to the script
• It is a file called $1
• It is a parameter to –f, indicating the size of the file
• It is a list of files that gets interpolated