A user on Photography has only 103 rep, and has the association bonus rights. So their rep without the association bonus is 3.
Yet they were able to post this answer to a protected question on the per-site meta. Reputation on per-site metas is shared with that on the main site.
At first I thought it's probably "internal meta rep", since I've earned the Mortarboard badge on a per-site meta for making a highly-voted post there. But this user has no other meta posts.
How were they able to answer a protected question without the necessary rep? Is the check not performed on meta sites? Or did the user exploit some flaw to allow them to post when it's ordinarily blocked?
Update: After some testing by Suvitruf, it appears users with the association bonus rights can answer protected questions, even though this is supposed to be prevented.