ANSWER
d. The amplitude is 2
period:
![(2\pi)/(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/54koo89yfeqyupiekmg2bcb9z0o1v0xrze.png)
Step-by-step explanation
The given function is
![f(t) = - 2 \cos(3t)](https://img.qammunity.org/2020/formulas/mathematics/high-school/y21q5w63yg2245i5a5xya1sdz1czqjlx4o.png)
This function is of the form,
f(t) = a cos(bt)
The amplitude of this function is |a|
where a=-2
![| - 2| = 2](https://img.qammunity.org/2020/formulas/mathematics/high-school/ioi1i4gzklyfcjr4bjjeq0tj3nkvy5b73s.png)
The period of this function is given by,
![T= (2\pi)/(b)](https://img.qammunity.org/2020/formulas/mathematics/high-school/wy0usc4q0tbnq3apcn2ejaknwssbz81ynn.png)
But b=3,
![T= (2\pi)/(3)](https://img.qammunity.org/2020/formulas/mathematics/high-school/rcvmruo2vx0bd657mhipzw00te90f8oiyh.png)
Option D is correct.