The author acknowledges that a cashless society is convenient and efficient, but points out the problem that the elderly and others can be left behind. The final sentence strongly asserts that support for these people and the option of cash must not be forgotten. Therefore, the correct option accurately captures the author's main point.
The other options are incorrect for the following reasons:
- 'It is inevitable that more stores will not accept cash.': The author views this as a serious problem, not an inevitable outcome to accept.
- 'The progress of going cashless should be slowed down.': The author recognizes it as an important step, not something to delay.
- 'Eventually everyone should become able to use digital devices.': The text does not make such an extreme claim; it advocates for support and options.