老师好，帮我看看请问这道题是选什么答案

答案选A，购入时，借：交易性金融资产-债券—成本    1570
                                            应收利息                                 30
                                             投资收益                                 15
                                        贷：银行存款                            1615
年末计提利息收益时，借：应收利息                                  30（1500*4%/2）
                                         贷：投资收益                               30