Explanation:

Explain 

Checking A-F:

Trade secrets could be anything ranging from designs and processes to methods or information. 

The above sentence is correct both grammatically and contextually.

Checking B-D:

Despite knowing that it won’t suit her she wanted to buy a jumpsuit.

The above sentence is also correct both grammatically and contextually.

Checking C-E:

He was supposed to go to school and he went to the theatre instead.

Here, as the sentence implies contrast in ideas, usage of the conjunction 'and' is absurd. Instead of 'and' 'but' should have been used. Hence, the sentence doesn't make any sense. The pair C-E is hence invalid.

Option D is hence the correct answer.