How to find angular acceleration....

The angular displacement of a particle is given by

𝜃= 〖6𝑡〗^2−4𝑡+6, where time ‘t’ is in second and 𝜃 is in rad. The angular acceleration of particle at t = 4 sec

a) 6 𝑟𝑎𝑑 𝑠^(−2)                       b) 24 𝑟𝑎𝑑 𝑠^(−2) 

c) 12 𝑟𝑎𝑑 𝑠^(−2)                     d) 48 𝑟𝑎𝑑 𝑠^(−2)