Dictionary / Vocabulary / 二つに一つ
ふたつにひとつ
one of two (possibilities, alternatives, etc.)
Also written 2つに1つ
我々は行くかとどまるか2つに1つだ。
We have the alternative of going or staying.
可能性は中立か戦争かの二つに一つだ。
The alternative possibilities are neutrality or war.
できることは抵抗か逃亡か二つに一つだった。
The alternative possibilities were resistance and flight.