[单选题]
A square coil of wire wreh7 -s.*j brss.g a9x/zm dc-ith 15 bgeufm7 l ;1t5turns and an area of $0.40 \; m^{2}$ is placed parallel to a magnetic field of 0.75 T. The coil is flipped so its plane is perpendicular to the magnetic field in 0.050 s. What is the magnitude of the average induced $emf$?
A. $6.0 \; V$
B. $36 \; V$
C. $45 \; V$
D. $90 \; V$
