[tex] _{1}^{1}H + _{7}^{15}N-->_{x}^{y}Element + _{2}^{4}He\\ \\ 1+15=y+4,y=12\\ \\1+7=x+2, x=6\\ \\_{6}^{12}Element = _{6}^{12}C\\ \\Answer\ is\ D. [/tex]
