40KC/m240\mathrm{KC} / \mathrm{m}^{2}40KC/m2
50KC/m250\mathrm{KC} / \mathrm{m}^{2}50KC/m2
60KC/m260\mathrm{KC} / \mathrm{m}^{2}60KC/m2
70KC/m270\mathrm{KC} / \mathrm{m}^{2}70KC/m2
No correct answer\text{No correct answer}No correct answer