Final answer:
The efficacy of risperidone in treating schizophrenia is best monitored by observing improved social interactions, as the medication aims to reduce hallucinations and delusions that impede social functioning.
Step-by-step explanation:
Risperidone is an antipsychotic medication used to treat various symptoms of schizophrenia, a serious mental illness that can affect thoughts, feelings, and behaviors. The most effective parameter for monitoring the efficacy of risperidone treatment in a client with schizophrenia would be A. Improved social interactions. This is because schizophrenia significantly impairs social functioning, and one key goal of antipsychotic treatment is to reduce psychotic symptoms such as hallucinations and delusions, which can lead to better engagement with others and overall improved social interactions. While risperidone can also affect other neurologic functions, options B, C, and D are not primary indicators of antipsychotic efficacy for schizophrenia.