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. $$\begin{array} { l l l } \text { index rationalizing } & \text { conjugate } & \text { principal square rootcube root midpoint } \\\text { complex numberlike radicals } & \text { radicand } & \text { imaginary unit } \quad \text { distance }\end{array}$$
-The ----------written i, is the number whose square is -1.

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