In the vast areas of northern China, the sunny weather in autumn is due to the influence of a, warm front b, cold front c and low pressure system.

This question examines common weather and weather.

Cyclone and anticyclone describe the airflow condition of weather system, and low pressure and high pressure describe the pressure condition of weather system. In fact, cyclone is a low-pressure system and anticyclone is a high-pressure system.

Characteristics and weather of low pressure (cyclone) and high pressure (anticyclone) systems

?

hurricane

anticyclone

atmospheric pressure

Low air pressure (low in the middle and high around)

High air pressure (high in the middle and low around)

Horizontal motion

Converging at the center in all directions (north to south)

The center diverges in all directions (north to south)

vertical motion

rise

water channel

weather

rainy season

How sunny and dry it is.

for instance

typhoon

Summer drought in the Yangtze River basin and crisp autumn weather in northern China

So choose option d in this question.