Which items in the list are primary sources a historian could use to contextualize why a political revolution occurred in egypt in 2011?

a letter written by a participant in the revolution
an article written by an american considering causes for the revolution
a historical text written about middle eastern revolutions over time
a photograph of political protests during the revolution
a. i, iii, and iv
b. iii only
c. ii and iv
d. i and iv