"most problematic one" is a correct and usable phrase in written English
You can use it when you want to point out the most difficult or complex problem in a given set of problems. For example: "The tax code is filled with complications, but the most problematic one is determining the correct tax rate."
Building stronger families means gripping the 120,000 most problematic ones and really addressing their problems, not leaving them in touch with, but untouched by, dozens of different agencies.
Among the tropospheric gases that can be monitored from space, ozone is one of the most problematic ones.
One of the most problematic branches on which to optimize characters was the branch leading to Alismatales.
In other words, the book of the Bible that the historical Church found most problematic is the one that American Evangelicals latched on to like flies on you know what.
The ToE is one of the most important theories in biology and yet a most controversial and problematic one to teach and learn.
The analysis under this category of the environmental effects is the most frequent and problematic one as compared to others.
Roden uses those lunches to test, and retest, her most problematic recipes, like the one for slow-roasted Andalusian lamb where the lamb ended up swimming in a thin puddle of honey, white wine, and rendered fat.
By excluding from the analysis the most problematic cases in which one probe set is informative and the other is not we elevated the percentage of cases with good correlation [see additional file 3].
One of the most problematic aspects of contract cheating, and yet one of the most appealing for those who use the services, is that it is hard to detect and the assignments usually pass (Lines 2016), although it is slightly easier to detect when markers are told that some assignments in a sample have been purchased (Dawson and Sutherland-Smith 2017).
Somewhat surprisingly, the supermarket proved to be the most problematic location for the artist: "On one occasion, I set the sculptures up in a grocery store and took pictures of them in the meat section.
