I can help you with that if you translate to English
Solution :
From the given data,
For the spherical shell is
where x is the radius of gyration and the acceleration of a rolling body on an inclined plane = a
Therefore,
= 0.6 x 9.81 x sin ( 29.7)
Δt = 1.411 s
In my estimation I would say C, I was leaning towards A, but I believe that would merely be "incomplete combustion." I hope this was semi-helpful!