tolong di jawab yah !

k₁ = k₂ = k
kp = nk
     = 2(300 N/m) = 600 N/m

1 / ks = 1 / kp + 1 / k₃
kp = k₃
ks = (2 / kp)⁻¹ = [2 / (600 N/m)]⁻¹ = 300 N/m

Δx = mg / ks
      = (3 kg)(10 m/s²) / (300 N/m) = 0,1 m = 10 cm
Jawaban: D.