Today, despite widely available technology such as high-resolution scanners and printers, counterfeiting is more difficult than it was at the time of the Civil War, when it was estimated that one-third of all currency in circulation was counterfeit. (A) Today, despite widely available technology such as high-resolution scanners and printers, counterfeiting is more difficult than it was at the time of the Civil War, when it was estimated that one-third of all currency in circulation was counterfeit. (B) Despite widely available technology such as high-resolution scanners and printers today, counterfeiting is more difficult than it was at the time of the Civil War, when it was estimated that one-third of all currency in circulation was counterfeit. (C) Despite widely available technology such as high-resolution scanners and printers, counterfeiting is more difficult than at the time of the Civil War, when it was estimated that one-third of all currency in circulation was counterfeit. (D) Today, despite widely available technology such as high-resolution scanners and printers, counterfeiting is more difficult than when it was estimated that one-third of all currency in circulation was counterfeit at the time of the Civil War. (E) Today, because of widely available technology such as high-resolution scanners and printers, counterfeiting is more difficult than it was at the time of the Civil War, when it was estimated that one-third of all currency in circulation was counterfeit. 答案是A选项。但是counterfeiting is more difficult than it was at the time of，这里不可以用it应该用that吧？