Correct Answer: A
Analysis:
A. 障碍(zhàngài) is the word for “Obstacle.”
The characters 障(zhàng) and 碍(ài) both mean obstacle.
B. 窗户(chuānghu) is the word for “Window.”
The character 窗(chuāng) means window, 户(hù) means household.
C. 机器(jīqì) is the word for “Machine.”
The characters 机(jī) and 器(qì) both mean machine.
D. 边缘(biānyuán) is the word for “Edge.”
The character 边(biān) means side, edge, brim and so on, 缘(yuán) means reason or edge.