What does this mean?

You are sitting in an airport preparing to use a free WLAN. When you look at the connections in your Windows 7 wireless client, you see a network name and three boxes with a yellow shield.

What does this mean?
A . You cannot connect to this WLA
C . An open ad hoc network is nearby.
D . The WLAN in the airport is open.
E . A secure ad hoc network is nearby.
F . A secure WLAN is in the airport.
G . You must provide a username and password to access the WLAN in the airport.

Answer: B