A block of mass $1\, kg$ is at rest on a horizontal table. The coefficient of static friction  between the block and the table is $0.5.$ The magnitude of the force acting upwards at  an angle of $60^o$ from the horizontal that will just start the block moving is
  • A$5 \,N$
  • B$\frac{20}{2 + \sqrt 3}\,N$
  • C$\frac{20}{2 - \sqrt 3}\,N$
  • D$10 \,N$
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