Interesting. IIRC, intelligence tests, SATs and the like abound in questions that test abstract thinking skills, like pattern-matching or analogies. That question seems to be a very, very rudimentary level of that class of question, and in fact not even that, because the instructions you mentioned fully explain what the pattern is. If someone couldn’t successfully figure out that pattern yet had an apparently normal functional life, I would attribute it to an older person who had very little or no formal education, to such an extent that they had never been exposed to even the most elementary abstract thinking.
OTOH, they might just be stupid. I’d be willing to bet that the Orange Ignoramus had to really think about that one; if his brain had a temperature-controlled fan like many CPU and GPU fans, it would have revved up to high speed for quite some time as his tiny brain struggled with the problem, at risk of overheating. In this case, the patient in question has never had a normal functional life (I’m about halfway through the Mary Trump book which clearly establishes that fact). On at least two occasions, as noted over here, he’s been defeated in a battle of wits by an umbrella, an inanimate object not known for its intellectual acumen.
It’s true that he’s a sociopath suffering from narcissistic personality disorder, but that does not preclude him from also being – in the immortal words of Rex Tillerson – a “fucking moron”. Or in the words of James Mattis, having an understanding of international affairs “on the level of a fifth- or sixth-grader”.