The masses to the nearest 0.5 kg of two parcels are 1.5 kg and 2.5 kg. Calculate the lower and upper bounds of their combined mass.
a) Lower bound: 2.0 kg, Upper bound: 3.5 kg
b) Lower bound: 2.5 kg, Upper bound: 4.0 kg
c) Lower bound: 3.0 kg, Upper bound: 5.0 kg
d) Lower bound: 3.5 kg, Upper bound: 5.5 kg