A particle is moving in the vertical plane. It is attached at one end of a string of length l whose other end is fixed. The velocity at the lowest point is u. The tension in the string is T and velocity of the particle is $\overrightarrow{\mathrm{v}}$ at any position. Then, which of the following quantity will remain constant.

• A

  $\overrightarrow{\mathrm{T}} .\overrightarrow{\mathrm{v}}$

• B

  Kinetic energy

• C

  Gravitational potential energy

• D

  $\overrightarrow{\mathrm{T}} \times \overrightarrow{\mathrm{v}}$