Two particles start simultaneously from the same point and move along two straight lines, one with uniform velocity \[\vec{u}\] and the other from rest with uniform acceleration\[\vec{f}\]. Let \[\alpha \] be the angle between their directions of motion. The relative velocity of the second particle w.r.t. the first is least after a time

• A. \[\frac{u\,\,\cos \,\,\alpha }{f}\]
• B. \[\frac{u\,\,\sin \,\,\alpha }{f}\]
• C. \[\frac{f\,\,\cos \,\,\alpha }{u}\]
• D. \[u\,\,\sin \,\,\alpha \]