In the reaction,
`CH_(3)-underset(**)overset(O)overset(||)(C)-NH_(2) underset(Delta)overset(P_(2)O_(5))rarr underset(**)(C)-=N`. The hybridization state of marked carbon atom changes from:
A. `sp^(2)` to sp
B. `sp^(3)` to sp
C. `sp^(3)` to `sp^(2)`
D. `sp^(2)` to `sp^(3)`