The correct answer was D (TI = 3s). Here’s what that looks like,
Figure 7.6:Inversion recovery image with TI = 3 s, TR = 5 s, TE = 15 ms, FA = 90 degrees
As you can see, ventricles are quite dark, meaning this TI nulls the ventricular signal. This is clearly deduced from Figure 2.3 by hovering the cursor over the white matter signal where it crosses 0.