What radial is the aircraft crossing? I'm working through the ASA Private Pilot 2020 Test Prep questions and there's a question I don't understand the answer for.

3579 (Refer to Figure 28, illustration 5) The VOR receiver has the
indication shown. What radial is the aircraft crossing?

A - 030
B - 210
C - 300



I thought the answer was B - 210 but that is the heading, not the crossing.
The correct answer is A - 030, but I'm not sure why. What does it mean to be crossing a radial?
A radial is always pointing (radiating) away from the VOR. But your instrument shows the TO/FROM indicator as TO. So you are crossing a 210 course towards the VOR, which means you are on the 030 radial from the VOR.

What does it mean to be crossing a radial?

This just refers to the fact that you cannot determine your heading (or track) from the CDI. Based on this instrument alone, you could be following the track to VOR right now or just happen to cross the radial at this moment (but actually fly in a totally different direction).