Final answer:
Rapid-readout biological indicators are the most current and absolute method for confirming that sterilization protocols have been correctly followed, by verifying the destruction of highly resistant bacterial endospores.
Step-by-step explanation:
The most current absolute indication that the proper sterilization time, temperature, and steam have been maintained is b. Rapid-readout biological indicators. These use the endospores of thermophilic bacteria like Geobacillus stearothermophilus, which are highly resistant to heat, to determine whether the sterilization protocol has effectively killed these organisms. In contrast, autoclave tape changes color to indicate that a specific temperature has been reached, but it does not confirm sterility since it does not measure exposure time or killing of the most resistant microbes. Spore strip indicators and Diack tubes are also used, but rapid-readout biological indicators provide the most immediate and definitive proof of sterilization.