Select the most appropriate collocating word to fill in the blank.

There is _______ traffic every morning.

heavy

The most appropriate collocating word to fill in the blank is heavy.

The word "heavy" is often used to describe traffic that is slow-moving or congested. It is the most appropriate option in this context because it conveys the idea of a lot of cars on the road.

The other options are either incorrect or do not make sense in the context of the sentence.

• "Long" can be used to describe traffic that is slow-moving, but it is not as specific as "heavy".
• "Big" can be used to describe traffic that is congested, but it does not convey the idea of a lot of cars on the road.
• "Lengthy" is not an appropriate word to use to describe traffic. It is more commonly used to describe something that is long in duration, such as a meeting or a book.