Pressure is defined as force per unit area. Mathematically, pressure (P) can be expressed as P = F/A, where F is force and A is the area. The unit of force is newton (N) and the unit of area is square meter (m2). Therefore, the unit of pressure is N/m2. This can be further simplified as kg m/s2 / m2 which gives kg m-1s-2. Therefore, option (B) is the correct answer.