It is unfortunate that demonstrations are taking place in birmingham, but it is even more unfortunate that the city's white power structure left the negro community with no alternative.

how does king support this claim?
by providing the names of corrupt public figures
by explaining birmingham’s segregationists laws
by quoting the racist sentiments of city leaders
by describing birmingham’s record of injustice

King said himself that

"[...]But when you have  seen vicious mobs lynch your mothers and fathers at will and drown your sisters and brothers at  whim; when you have seen hate filled policemen curse, kick and even kill your black brothers and  sisters; when you see the vast majority of your twenty million Negro brothers smothering in an  airtight cage of poverty in the midst of an affluent society[...]"

King said everything that the African Americans have lived through and this is just a part of the many injustices committed towards them that he described without the need of mentioning anyone or any law.

The answer is:

by describing Birmingham’s record of injustice

.elections are held to determine who serves in congress.