a. 750 km
b. 755 km
c. 765 km
d. 770 km
Explanation:
The longest single flash that covered a horizontal distance of 768 ± 8 km (477.2 ± 5 miles) across parts of the southern United States on 29 April 2020. This is equivalent to the distance between New York City and Columbus Ohio in the United States or between London and the German city of Hamburg.