7.在$\frac{m}{3}$、$\frac{{{x^2}+1}}{2}$、$\frac{3xy}{π}$、$\frac{3}{x+y}$、$a+\frac{1}{m}$中分式的个数有( )
0 286767 286775 286781 286785 286791 286793 286797 286803 286805 286811 286817 286821 286823 286827 286833 286835 286841 286845 286847 286851 286853 286857 286859 286861 286862 286863 286865 286866 286867 286869 286871 286875 286877 286881 286883 286887 286893 286895 286901 286905 286907 286911 286917 286923 286925 286931 286935 286937 286943 286947 286953 286961 366461
| A. | 2个 | B. | 3个 | C. | 4个 | D. | 5个 |