Answer-Civilization develop(A) a complex way of life(B) that came about as urban(C) began to describes(D) n...

The pluralbase verb develop doesnt justify the singular subject civilization according to the subject-verb agreement rule. Describes is a singular verb. It fits perfectly in the first position. So, A and D should be interchanged. The base verb develop fits perfectly in the fourth position as it follows the infinitive marker to which requires a base verb after it. The word urban in, relating to, or characteristic of a town or city is an adjective. It doesnt fit in the third position as there should be a noun as it follows the preposition as. The word fits in the last position as the adjective qualifies the noun settlements. Also, the noun people becomes the subject of the verb began. So, C and E should be interchanged. The noun people fits perfectly in the third position. Hence, option d is the correct answer. The correct sentence is Civilization describes a complex way of life that came about as people began to develop networks of urban settlements.