The term "vitiates" means to spoil or destroy the validity of something. Therefore, the question is asking which of the following actions would invalidate or make the act of Salah (Islamic prayer) invalid.
Out of the four options given - intoxication, adornment, falsehood, and yawning - the one that vitiates Salah is intoxication.
If a person is intoxicated or under the influence of drugs or alcohol, their ability to concentrate and perform the prayer properly is compromised. As a result, their prayer may not be considered valid in the eyes of Allah.
However, it's important to note that there are certain conditions under which a person can still perform Salah while under the influence of medication or drugs, such as in cases where the medication is necessary for their health.
Adornment, falsehood, and yawning, on the other hand, do not invalidate Salah. Adornment refers to wearing jewelry or clothing during prayer, which is not prohibited in Islam. Falsehood refers to lying or deceiving, which is obviously not an acceptable behavior in Islam but does not necessarily invalidate the prayer itself. Yawning is a natural bodily response and does not affect the validity of the prayer.
In summary, the only action out of the given options that would vitiate Salah is intoxication, which can compromise the person's ability to perform the prayer properly.