5. An electricity meter shows 12486kWh at the beginning of a month and 12736kWh at the end. Two tariff plans are available:
Plan A: Flat rate Rs 6 per unit (kWh)
Plan B: Rs 5.50 per unit for the first 200 units and Rs 7 per unit for any additional units.
Which plan is cheaper for that month, and by how much?
a) Plan B, cheaper by Rs50
b) Plan A, cheaper by Rs50
c) Plan B, cheaper by Rs125
d) Plan B, cheaper by Rs100