设集合 $A=\left\{1,2\right\},B=\left\{1,2,3\right\},C=\left\{2,3,4\right\}$ ,则$\left(A\cap B\right)\cup C$=（   ）

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                                                                                                        汉江 临 泛

                                                                                                         (唐) 王 维

                                                                                           楚塞①三湘②接，荆门九派通。

                                                                                           江流天地外，山色有无中。

                                                                                           郡邑浮前浦，波澜动远空。

                                                                                           襄阳好风日，留醉与山翁③。

【注释】①楚塞：楚国的边界。战国时这一带本为楚地。②三湘：漓湘、潇湘、蒸湘的总称，在今湖南境内。③山翁：指晋代山简，竹林七贤山涛之子。曾任征南将军，好饮，每饮必醉。