"C'est le garçon auquel je pense."
We're offered one correct answer: "It is the boy I am thinking." This misses the preposition; it should be "It is the boy I am thinking about," since one can't 'think a boy' in English, or in French, for that matter.
I am not quite sure the English is perfectly correct. I would have said "he (or 'this') is the boy I am thinking of (or 'about') ".
I decided to try to keep the heart, so I went for rigid and "proper" English: This is the boy of whom I think (something I wouldn't normally say). It was accepted.
The bottom line here is: the better and less machine-like your translation is, the less likely it is to be accepted... You either can put up with it or you can't... I'm leaning towards the latter...
I feel like this should be 'he's the boy I'm thinking about' or similar, not 'it'
"of whom" is correct for "auquel" here, but when I tried "of whom" in one of the other sentences in this lesson, it was rejected because only "to whom" was a correct translation. Is this just context dependent?