An electron, initially traveling in the +x-direction with a speed of 4 x 105 m/s, enters a uniform electric field directed vertically upward. After traveling in this field for 3.5 x 10-7 s, the electron's velocity is directed 60o above the x-axis. What is the strength of the electric field?
a. 14.5 N/C
b. 11.3 N/C
c. 8.3 N/C
d. 6.5 N/C
e. 5.3 N/C