The consumer price index is a measure that detects monthly changes in the retail prices of goods and services. The payment of some government retirement benefits is based on the consumer price index so that those benefits reflect the change in the cost of living as the index changes. However, the consumer price index does not consider technological innovations that may drastically reduce the cost of producing some goods. Ttherefore, the value of government benefits is sometimes greater than is warranted by the true change in costs. The reasoning in the argument is most vulnerable to the criticism that the argument ['presumes, without providing warrant, that retirement benefits are not generally used to purchase unusual goods', 'fails to consider the possibility that there are years in which there is no change in the consumer price index', 'makes an irrelevant shift from discussing retail prices to discussing production costs', 'fails to make explicit which goods and services are included in the consumer price index']