Answer:
B.6.86 m
Step-by-step explanation:
Given that
Compression in spring ,x= 9 cm
Spring constant ,K= 830 N/m
Mass of the rocket ,m= 50 g = 0.05 kg ( 1 kg = 1000 g)
Now by applying energy conservation


Now by putting the values ( we are taking g= 9.81 m/s²)

h= 6.853 m
Therefore the answer is B.
B.6.86 m