The phrase "a third alternative for" is correct and usable in written English.
It can be used when discussing options or choices, particularly when presenting an additional option alongside two others.
Example: "In addition to the two existing solutions, we should consider a third alternative for addressing the issue."
Alternatives: "an additional option for" or "a different choice for".
There was talk of even a third alternative for the company, specifically a self-help restructuring that could have included a spinoff of its television stations.
A third alternative for the absence of XMRV in our samples could be that the XMRV found in other studies is an inadvertent laboratory contaminant, which has been reported before for other viruses, including another MuLV-related virus [25].
More recently, external cephalic version (ECV), the manipulative transabdominal conversion of the breech to cephalic presentation, has come to be recognised as a third alternative for uncomplicated breech presentations at 37+ weeks for low risk patients.
A second alternative for not detecting XMRV in seminal plasma could be that the virus is cell-associated, and might be found in semen, but not in seminal plasma.
A second alternative for determining the maximum allowed utilization rate was to use the previous year's actual utilization rate.
Recently, though, there's been a third alternative: art for the script's sake.
A third alternative technique for identifying the inhibition of autophagy is measuring p62 protein upregulation [16], [34].
A third alternative explanation for the observed PEEP-related effect might relate to persistent inspiratory muscle activity during exhalation [ 29, 30].
A third alternative method for the enrichment of CD4+CD25+ T cells in the rheumatoid joint is related to the observation that synovial T cells are actively inhibited from undergoing apoptosis, thereby expanding their lifespan compared with their peripheral counterparts.
Then, in 1830, Edwin Beard Budding, an engineer from Gloucestershire, came up with a third alternative — "a machine for mowing lawns, etc".
The failures of utilization management in the 1990s demonstrated the need for a third alternative to better align incentives, such as bundling payment for an episode of care.
