These studs are not pink at all. Don't trust your eyes, they're purple, or magenta, as the specs from Lowe's tell us. However, thy're so common in the South, and surprise people from other locations, so I tried to dig into it a little bit and see what I could find.
As it turns out, it's a marketing ploy, from a lumber mill in the post WWII housing boom, to differentiate their product of good, southern pine, from the erstwhile Douglas Fir studs that were competing in the market. If you want good, Southern Pine, buy the purple studs. From this source.
During the post-World War II housing boom, a company called Temple-Inland introduced the now infamous purple 2×4 studs as a marketing tactic to compete against Douglas fir studs from the Pacific Northwest. It seems a sawmill owner in Southeast Texas had been painting his product orange and had no trouble selling all he could produce. Temple-Inland’s Sales Manager at the time, Bob Westin, presented stud samples in five different colors of water-repellant paint to the other members of the sales team. They unanimously selected the magenta (or purple as it is now referred to) and the rest is history.I don't know which mill made the studs I use. I went out to look and couldn't find any marking at all on them, but it seems that the pink studs (sorry, purple studs) are a post WWII marketing ploy that endures to this day. Down here in the South, we us pink (sorry, purple) studs and don't give it a second thought. They're made of good, strong Southern yellow pine, and that's the way it's been for as long as I can remember.
UPDATE: Anonymous asked in comments;
Am curious why the sink is that far from restroom plumbing - is it an issue with sewer line routing ? Not complaining mind you (its your place !), just curious.The simplest answer is that is where she wants the sink. My plumber says that it is not a problem and we've got a simple solution for the drain. If my gal wants the sink centered o the back wall, that's exactly what I'm going to give her.