Given a file called birthdays containing lines like: YYYY-MM-DD Name 1983-06-02 Tim 1995-12-17 Sue Which command would you use to output the lines belonging to all people listed whose birthday is in…

The pattern '[56]' matches any line containing a 5 or 6 anywhere, including year digits or day digits, producing many false positives unrelated to May or June.

In basic regular expressions, '?' makes the preceding character optional, so '05?6?' matches strings like '0', '05', '06', or '056' but does not reliably isolate the month field as 05 or 06.

The pattern '[0-9]*-0[56]-' anchors the match to the month position by requiring a literal '-0' before the character class '[56]', which matches either 5 or 6, followed by another '-'. This precisely targets months 05 and 06 in the date field without matching digits elsewhere in the line.

Piping 'grep 06' into 'grep 05' requires both substrings to appear on the same line simultaneously, which is impossible for a single date value and would match nothing.