Question

what role does the automated surface observing systems (asos) play in weather forecasting?
it is a fleet of weather balloons.
it is a system of radar sensors used to track storms.
it is the nations primary weather - observing network.
it provides weather reports much like the national weather service.

Explanation:

ASOS is a network of weather - observing stations across the nation. It is not a fleet of balloons (which are a different type of weather - observing tool), not just a system of radar sensors (it has multiple sensors including for temperature, humidity, etc., not just radar for storms), and it is an observing network rather than just providing reports like the National Weather Service (the NWS may use ASOS data but they are different entities).

Answer:

It is the nation's primary weather - observing network.