Final answer:
The sentence should be filled in with (b) 'cold' to accurately describe the type of front stretching from the Iowa Low into northern Texas, which is associated with a significant drop in temperature.
Step-by-step explanation:
The Iowa Low is a reference to a low-pressure system typically found in meteorological discussions. In the context of the sentence given, the blank is most accurately filled with the word cold. Therefore, the corrected sentence should read: "Also from the Iowa Low, a cold front stretched generally southwestward curving into northern Texas." The characteristics of a cold front include a noticeable drop in temperature as cooler air displaces warmer air. This often results in a sharp change in weather and can be accompanied by storms or other precipitation as the cold air forces the warm, moist air to rise and condense.
As the cold front moves into a locale, the temperature will decrease significantly. This drop in temperature can be abrupt and substantial, as indicated by the statement that it can decrease by 40.0 Fahrenheit degrees. After the initial passage of the front, temperatures will usually continue to adjust, oftentimes warming up slowly as the colder air mass settles and begins to mix with the surrounding environment.