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In which decade were the first successful diode and triode vacuum tubes invented?

A: 1800s

B: 1880s

C: 1890s

D: 1900s

Explanation: In 1904, John Ambrose Fleming invented the first practical electron tube called the 'Fleming Valve', which is a diode rectifier. In 1906, Lee de Forest invented the audion later called the triode, which provided signal amplification.