ANS:B - smoothen the power impluses.

A flywheel is provided in a machine primarily to smooth out power impulses. A flywheel is a rotating mechanical device that stores rotational energy. In machines and engines, particularly those with reciprocating motion (such as piston engines), the rotational motion of the flywheel helps to even out the fluctuations in power output caused by the periodic nature of the power source or the load. This smoothing effect helps maintain a more constant speed of rotation and reduces vibrations, thereby improving the overall efficiency and performance of the machine. While a flywheel may contribute to the structural strength of the shaft indirectly by providing additional mass and rigidity to the rotating assembly, and it may assist in starting a machine by storing kinetic energy, these are secondary functions compared to its primary purpose of smoothing out power impulses. Therefore, the correct answer is smoothen the power impulses.