Explanation

Creating a filter: as we make our way through the original sentence, we may not spot any candidate for error. The phrase started with "invented" properly modifies "magnetron," for example. We'll look for objective errors and come back to (A).

Finding objective errors: in (B), putting the two long modifiers in a row is inferior style, and "having the ability" is inferior to "able," so (B) is out. Choices (C), (D) and (E) are all similar. In all three, "called the cavity magnetron" is improperly constructed as a modifier set off by commas. Properly it's an elided restrictive clause standing for "that was called the cavity magnetron" and belongs closer to "technology" and not set off by commas. Conceptually, it defines the word "technology" and should be close to it. Choices (C) through (E) also distort the intended meaning of the sentence, because the cavity magnetron is what the sentence is about and the focus has shifted away from it. The correct answer is (A).