6 A single sheet of aluminium foil is folded twice to produce a stack of four sheets. The total
thickness of the stack of sheets is measured to be (0.80 ± 0.02) mm. This measurement is made
using a digital caliper with a zero error of (−0.20 ± 0.02) mm.
What is the percentage uncertainty in the calculated thickness of a single sheet?

A 1.0% B 2.0% C 4.0% D 6.7%