The position vector of a particle changes with time according to the relation \(\vec r\left( {\rm{t}} \right) = 15{{\rm{t}}^2}{\rm{\hat i}} + \left( {4 - 20{{\rm{t}}^2}} \right){\rm{\hat j}}\). What is the magnitude of the acceleration at t = 1?

• A. 40
• B. 25
• C. 100
• D. 50