What regular expression does the pattern 'lab[ex]*' match in 'grep'?

The regular expression pattern lab[ex]* matches any string that starts with "lab" followed by zero or more occurrences of either "e" or "x".

Here are some examples of strings that would match this pattern:

• lab
• labe
• labex
• labexex
• labeex

In summary, it matches "lab" followed by any combination of "e" and "x", including none at all.