You will be asked certain questions by an officer during a routine DUI stop. An officer needs probable cause for intoxication before he can arrest you for suspicion of driving under the influence. There are several different ways to obtain probable cause.
Oftentimes, to be compliant, drivers will admit to having been drinking. These statements can be used against you. You have the Fifth Amendment right to remain silent and not say anything that could incriminate you. If you do offer an admission, it can later be used as proof of your intoxication, or in the very least of you having consumed alcoholic beverages. Lets consider an example.