Every voltage cell has an internal resistance R. To obtain the maximum current from joined cells means to find group them together is such a way that the resulting internal resistance is minimised.
1. The series grouping provides maximum internal resistance for the group (`R_(eq) = R +R +R+... ` , or `R_(eq) =n*R` )
2.The parallel grouping provides the minimum internal resistance for the group (`1/R_(eq) =1/R +1/R +1/R +...` , or `R_(eq) =R/n` )
3.The mixed combination grouping provides an intermediate value for the resistance of the group between the maximum and minimum values found above.
4. Because as shown above there is a maximum and minimum value for the equivalent total resistance `R_(eq)` this choice is not correct.
Therefore the correct answer is 2) In parallel.