Unknown m melts at 112 degrees Celsius. Known compounds 3-nitroaniline and 4-nitrophenol both melt at 112-114 degrees Celsius. A mixture of B and 4-nitrophenol melted at 90-98 degrees Celsius. Identify m.
a) 3-nitroaniline
b) 4-nitrophenol
c) benzoic acid
d) cannot be determined