Fill in the Blank with One of the Words or Phrases

Multiple Choice

Fill in the blank with one of the words or phrases listed below.

- $\mathrm { A } ( \mathrm { n } ) \quad$ ــــــــــــــــis a number that can be written in the form $a + b i$ , where a and b are real numbers.

A) conjugate
B) imaginary unit
C) index
D) complex number