Ram ans Shyam purchased two electric tea kettles A and B of same size, same thickness, and same volume of 0.4L. They studied the specification of kettles as under `Kettle A: ` specific heat capacity `= 1680 Jkg^(-1)K^(-1)` Mass = 200 g Cost = Rs. 400 Kettle B: Specific heat capacity = `2450 Jkg^(-1) K^(-1)` Mass = 400 g Cost = Rs. 400 When kettle A is switched on with constant potential source, the tea begins to boil in 6 min. When kettle B is switched on with the same source separately, then tea begins to boil in 8 min. The efficiengy of kettle is defined as (Energy used for liquid heating)/(Total energy supplied) They made discussion on specification and efficiency of kettles and subsequently prepared a list of questions to draw the conclusions. Some of them are as under (assume specific heat of tea liquid as `4200J kg^(-1)K^(-1)` and density `1000 kgm^(-3)` Efficiency of kettle A isA. `63.34%`B. `83.34%`C. `93.34%`D. `73.34%`