Final answer:
The sentence with the illogical construction is: 'For two singers in Don Giavanni, an opera by Mozart, contains the famous duet 'La ci darem la mano.'' where the connection between the first part and the second part of the sentence is not logical.
Step-by-step explanation:
The sentence that contains a mixed or illogical construction is: "For two singers in Don Giavanni, an opera by Mozart, contains the famous duet 'La ci darem la mano.'"
In this sentence, the first part 'for two singers in Don Giavanni' is not connected logically to the second part. A more logical construction would be: 'Don Giavanni, an opera by Mozart, contains the famous duet 'La ci darem la mano' for two singers.'
So, sentence b is incorrect, while both sentence a and sentence c are correct.
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