A mass of 0.1 kg is rotated in a vertical circle using a string of length 20 cm. When the string makes an angle 30^o with the vertical, the speed of the mass is 1.5ms^–1. The tangential acceleration of the mass at that instant is

• A

  4.9 ms^–2

• B

  9.8 ms^–2

• C

  2.45 ms^–2

• D

  19.6 ms^–2