The correct option is
A As long as
Option A - 'As well as' means 'also'. For example, 'She likes vanilla as well as chocolate ice cream.' The given sentence doesn't explain about more than one idea/person/thing. Thus option A is incorrect.
Option B - 'Since' is used to explain an action that started at a given time in the past and is ongoing in the present and might continue in the future. For example, 'I haven't gone to London since 2008.' As the given sentence doesn't explain an event that took place in the past and is ongoing in the present, we can't use 'since' here. Thus option B is incorrect.
Option C - 'So that' is used to explain a purpose or give a reason. For example, 'I worked hard so that I get the promotion.' As the given sentence doesn't explain or have a purpose or a reason, we can't use 'so that' here. Thus option C is incorrect.
Option D - 'As long as' means 'if/ until the time'. For example, 'As long as you work, you will have enough money.' As the given sentence explains a condition, we can use 'as long as' here. Thus option D is the correct answer.
'As long as Sachin plays, we need not worry about winning.'