Answer: B. "So far each task had proved to be more complicated than it seemed at first.
Step-by-step explanation:
The sentence from the passage that supports the statement "Kari checks to see if the edge of the field can be lifted because she realizes that each previous task required a creative solution" is option B " So far each task had proved to be more complicated than it seemed at first".
Since she didn't realise how difficult the task were at first and later realised how complicated the previous tasks were, this made Kari check to see if the edge of the field can be lifted. This will enable Karl avoid the difficulties involved involved.
Therefore the correct option is B.