The nurse admits a patient with a serious medical condition. During the assessment, the focus is on physical problems. The presence of substance abuse does not become apparent until the patient develops symptoms of

A. respiratory problems These may occur with some drugs (like opioids), but are not a general indicator that someone has a substance use disorder. B. depression problems Depression might co-exist with addiction, but it doesn't reveal the substance abuse unless directly linked. C. withdrawal problems Substance abuse often becomes evident when the patient enters withdrawal, especially in a controlled environment like a hospital where access to substances is restricted. D. cardiac problems Some drugs can affect the heart, but cardiac issues alone do not necessarily point to substance abuse.