Final answer:
In chapter 46 of 'Great Expectations', Pip and Herbert engage in rowing, not one of the options listed, as a cover for their escape plan for Magwitch.
Step-by-step explanation:
In chapter 46 of Great Expectations, Pip and Herbert take up rowing as the sport to cover their plans to help Magwitch escape. While rowing is not one of the options provided in the question, it is the activity they engage in to condition themselves and to familiarize themselves with the river, which is crucial for the escape plan. Neither cricket, football, rugby, nor tennis is mentioned in this context.