执行以下代码后，file.txt 文件的内容是？（ ）

with open('file.txt', 'w') as f:
         f.write('First line\n') 
with open('file.txt', 'a') as f: 
         f.write('Second line\n') 
with open('file.txt', 'r+') as f: 
         f.seek(0)
         f.write('Replaced first line\n')