Respuesta :

t=0, d=0 so ans B is wrong

t=0, dd/dt <0 as it is propelled downward so ans C is wrong

ang vel = 2[tex] \pi [/tex] / period

= 2[tex] \pi [/tex] / 4.5

= 4[tex] \pi [/tex] / 9

so D is the correct answer