(D) 2.8 cm
Given, BC = 3cm and ∠C=60∘
We know that, the construction of a triangle is possible, if sum of two sides is greater than the thirde side of the triangle i.e.,
AB+BC>AC
⇒ BC>AC−AB
⇒ 3>AC−AB
So, if AC – AB = 2.8cm, then construction of ΔABC with given conditions is possible.