The answer is a
Hope this helps!
Explanation:
By Hooke's Law,
F=kx
The only force acting here is weight, and x is the extension of the string (you need to convert this to mm) so
mg=kx
(0.15)(9.81)=k ((420-300)x10^-3)
Then just solve this equation.
Getting it right because you do not want to spread false information. To be first isnt always the best, sure you might feel better being the first, but you won’t always get it right.
