In this task, you are given a sentence from the research paper and your task is to classify the given sentence into the following categories: Background (Why is this problem important? What relevant works have been created before? What is still missing in the previous works? What are the high-level research questions? How might this help other research or researchers?), Purpose (What specific things do the researchers want to do? What specific knowledge do the researchers want to gain? What specific hypothesis do the researchers want to test?), Method (How did the researchers do the work or find what they sought? What are the procedures and steps of the research?), or Finding (What did the researchers find out? Did the proposed methods work? Did the thing behave as the researchers expected?). 

Example Input: international collaboration among scientists is essential to address these risks and prevent the next pandemic.
Example Output: purpose

Example Input: cell apoptosis , and interferon ( IFN ) signalling was studied by flow cytometric analysis and quantitative RT - ( q ) PCR using shBCN1-MDBK cells.
Example Output: method

Example Input: The purpose of this review is to summarize the achievements of using self-replicating RNA viruses for RNA therapy based on preclinical animal studies and clinical trials in humans.
Example Output:
purpose