The correct answer is A. 2.5 m.
Contraction joints are used in rigid pavements to control cracking. They are placed perpendicular to the traffic flow and allow the pavement to expand and contract without developing cracks. The spacing of contraction joints is determined by a number of factors, including the type of pavement, the climate, and the traffic loading. In general, the maximum spacing of contraction joints is 2.5 m.
Option B is incorrect because the maximum spacing of contraction joints is 2.5 m, not 3.5 m.
Option C is incorrect because the maximum spacing of contraction joints is 2.5 m, not 4.5 m.
Option D is incorrect because the maximum spacing of contraction joints is 2.5 m, not 5.5 m.