Student or Learner
In this type of the test of Toefl, each sentence has four underlined words or phrases. The four underlined parts of the sentence are marked A, B, C, and D. We have to identify the one underlined word or phrase that must be changed in order for the sentence to be correct.
The technique of spectroscopy allows analyst of incoming light after it has been separated into its component wavelenghts by passage through a prism.
The correct answer is A. However, I can't understand this question. A should be replaced with?