I have been doing some English tests (for admission in a University, mark you), and the second part of these tests consists of a grammatical section. The third part of the grammatical section is Error Identification. The directions read as follows: Some of the sentences below contain an error in the grammar, usage, word choice or idiom. For each sentence, select the one underlined part that contains the mistake and then, on your answer sheet, fill in the space that corresponds to the letter of the answer you have chosen. If there is no error in the sentence, mark answer D.

And here is the sentence that troubles me:

Today's problems (A) are different from those that (B) we faced when we were younger; they appear to be less involved (C). No error (D)

I was quite sure that the mistake was in C and that the correct form should be 'less invloving' (viz. the problems). But the 'correct' answer according to the test booklet in D No Error. And so my question is, whether such a sentence is at all logically possible in English, or was I initially correct in pointing out the mistake?
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Comments  (Page 2) 
The problem with this test question appears to be that the statement itself is untrue, since the test question seems pretty involved (complicated).