Form input: Hidden vs Disabled, after changing default option

Currently, I am designing a form that has a radiobutton group for a certain question, that affects whether a second radiobutton group is relevant to them or not. Now I've been researching on what is the best option in regards to showing (but disabling) or hiding this second radiobutton group.

The vast majority of the users (say 80%) will choose the default option in question one, after which the second input will be relevant to them. The remaining percentage will choose on of the other options.

The second input will initially always be visible, and it is linked to the first option of the first input. But what would be the best solution for the second option? I personally think hiding it should be fine, as it will be completely irrelevant for anyone choosing any of the other options in the first input. If we would have it remain visible, we would have to add a message that tells the user why the input has been disabled, which would increase cognitive load.

The image above shows a simplified version of the case. The default state is shown on the left. The middle image shows the "hide" design, while the third image on the right shows the "disable" design.