develop nuclear weapons.
As another commenter said already, Canada went through nuclear disarmament in 1984. (The US wasn't pleased.) "Develop" is definitely the wrong word.
Just for your convenience, then, here are all the statistics from the paper:
And just because it's so important to the science, the rest of the results:
When correlating PHs (square root) with GM segmentations, we found a significant negative association in the right striatum, namely caudate nucleus (based on the automated anatomical labeling atlas34; peak voxel: x=11, y=5, z=3; P<.001; corrected for multiple comparisons) (Figure 1A). When we used a lower threshold of P<.005, an additional cluster in the left caudate reached significance (x=6, y=0, z=6), showing that the effect is not clearly lateralized. We refer to the cluster as the striatum; however, for the subsequent discussion, it is noteworthy that the cluster overlaps with a reward processing literature-based probabilistic region of interest of the ventral striatum, created by means of in-house software35 (predominantly monetary-incentive delay task, see eAppendix in Supplement for details).
As for alternative hypotheses, the only one they present is "Individuals with lower striatum volume may need more external stimulation to experience pleasure and might therefore experience pornography consumption as more rewarding, which may in turn lead to higher PHs."
One man's constant is another man's variable. -- A.J. Perlis