What are the two holiest cities in islam? select all that apply
baghdad
cairo
jerusalem
mecca
medina
riyadh

The holiest place in Islam is Mecca - this is where the Prophet Muhammad was born and all Muslims are required to make a pilgrimage there once in their life. 

Muhammad's tomb is in Medina and this is the second holy site of Islam - so the answer is Mecca and Medina. 

however, Jerusalem is also a holy site in Islam, as it was a place where previous prophets were - so the question should ask for three holy cites.