1. 
candle     lamp   floodlight
hut     cottage ?

A. tent
B. city
C. dwelling
D. house

Answer: Option D

Explanation:

Above the line, the relationship shows a progression of sources of light. The relationship below the line shows a progression of types of housing, from smallest to largest. (Choice a) is incorrect because a tent is smaller than a house. Choices b and c are wrong because they are not part of the progression.