阅读短文，选出填入空格最合适的一项： Last year, many custo…

阅读短文，选出填入空格最合适的一项：

Last year, many customers complained that the bank's mobile app was slow and hard to use. ___ these complaints, the bank redesigned the app, cutting the number of steps needed to make a payment from six to three. Since the update, customer ratings of the app have risen sharply, and fewer people are calling the help line. The bank now plans to test every new feature with a small group of customers first.