The correct answer is: B. have been degrading.
The quality of products has been degrading over time. This is because products are often made with cheaper materials and are not built to last as long as they used to. Additionally, products are often not properly maintained, which can lead to them breaking down sooner.
Option A, “are degrading,” is incorrect because it implies that the quality of products is currently degrading. However, the quality of products has been degrading over time, so this option is not accurate.
Option C, “have degrading,” is incorrect because it is grammatically incorrect. The correct verb tense to use in this sentence is “have been degrading.”
Option D, “were degraded,” is incorrect because it implies that the quality of products was degraded at a specific point in time. However, the quality of products has been degrading over time, so this option is not accurate.