If one of the alternative acts required by an obligation is such as the law will not enforce, or if it becomes unlawful or impossible of performance, the obligation is to be interpreted as though the other stood alone.
N.D. Cent. Code § 9-01-20
Option - Valid act prevails
Official source: North Dakota Legislative Branch. Reproduced from public-domain North Dakota statutes; confirm against the official source for the current text. Not legal advice.