29.5mg of an organic compound containing nitrogen was digested according to Kjeldahl's method and the evolved ammonia was absorbed in 20mL of 0.1M HCl solution. The excess of the acid required 15mL of 0.1M NaOH solution for complete neutralization. The percentage of nitrogen in the compound is
(a) 29.5
(b) 59.0
(c) 47.4
(d) 23.7
