A particle of mass 0.3 kg is subjected to a force $F = -kx$ with $k = 15 \mathrm{~N}/\mathrm{m}$. What will be its initial acceleration if it is released from a point 20 cm away from the origin?
(1) $3 \mathrm{~m}/\mathrm{s}^2$
(2) $15 \mathrm{~m}/\mathrm{s}^2$
(3) $5 \mathrm{~m}/\mathrm{s}^2$
(4) $10 \mathrm{~m}/\mathrm{s}^2$