Alertly vs raptly

[Monica]

In the following fill-in-the-gap exercise:
Some other nations did the occasional scrawl when listening ..., but the British were undoubtedly the most compulsive of all those attending.

a ecstatically B calmly C raptly D alertly
Obviously, the correct option is C raptly, but I was wondering about the meaning of "listening alertly", I feel it means to listen as if expecting the other person to make a mistake or say something objectionable. Am I correct here? Thank you.

[Molly]

Here what an extract from the BNC says:

"It is very easy to take other people for granted and not to work on our relationships, but they do need continuous attention. They are often the most important feature of our lives, but very often the most neglected. Let's start by having a look at the skill of listening and how that can help in a relationship.

Listening alertly

Listening alertly is trying to understand what people are saying rather than just hearing the sounds that someone makes. It is a skill which can be developed --; but it is not easy and requires a great deal of hard work."

http://corpus.byu.edu/bnc/x.asp