How did Christianity spread? Include 2 pieces of information from page 6

(Page 6 in the picture below)

Early Christianity was primarily an urban faith, establishing itself in the city centers of the Roman Empire. Most of the people lived close together in crowded tenements. There were few secrets in such a setting. The faith spread as neighbors saw the believers' lives close-up on a daily basis.Explanation:

the correct labels are as follows:

a: yellow river

b: himalayan mountains

c: north china plain

d: taklimakan desert

its kind of blury sorry