We issue an at command but omit $-$f filename$)$ What is the result?

Group of answer choices

at responds with garbled time

nothing happens $($no error but at does not schedule anything$)$

we are dropped into the at$>$ prompt to enter the task$($s$)$ to schedule

we are dropped into the at$>$ prompt to enter the script$$s filename

atd automatically uses the file $.$at$\_$job found in your home directory