An administrator needs to examine two text files and select identical lines from the files. Which of the following commands wooW BEST accomplish this task?

Concatenating both files with cat and piping through awk to extract a target field, then counting results with wc, identifies content that appears identically across both files by measuring field-level repetition. This pipeline uses standard POSIX utilities to process and compare line content between two sources.

'sort | uniq -d' reports lines that are duplicated in the combined output but cannot distinguish lines duplicated within a single file from lines that are identical across both files.

'grep -v < report1' uses report1 as a pattern source to exclude matching lines, which selects lines that differ rather than lines that are identical.

'sort -u | diff' compares sorted unique output against no second argument, producing a usage error rather than identifying common lines between the two files.