Knowledge in all fields is expanding and Ph. D. students take longer than ever before -- sometimes eight years -- to complete degree requirements. Yet, instead of agreeing that the longer period is needed, some noted scholars are recommending that Ph. D. programs reduce their requirements and have students finish within three years. Which one of the following, if true, would most contribute to a justification of the noted scholars' recommendation? ['Quality of research matters more than quantity, even though, on average, the more time a Ph. D. student spends on research, the greater the quantity of research produced.', 'For at least the last 50 years, no researcher has been able to be conversant with any more than a small fraction of the existing knowledge within any given field.', 'The most important objectives of Ph. D. programs can be adequately fulfilled with the reduced requirements recommended.', 'Some unusually talented Ph. D. students already complete all Ph. D. requirements within three years.']