A Quadrillion has _________ zeros?

A Quadrillion has _________ zeros?

A. 15 zeros
B. 18 zeros
C. 21 zeros
D. None of these

Thousand, Million, Billion, Trillion, Quadrillion, Quintillion-each comes with three additional zeroes. Even though there are names beyond Quintillion.
The numbers are written with scientific notation to make them easier to read and understand.

Name Number
Million 1 x 106
Billion 1 x 109
Trillion 1 x 1012
Quadrillion 1 x 1015
Quintillion 1 x 1018
Sextillion 1 x 1021
Septillion 1 x 1024
Octillion 1 x 1027
Nonillion 1 x 1030
Decillion 1 x 1033
Undecillion 1 x 1036
Duodecillion 1 x 1039
Tredecillion 1 x 1042
Quattuordecillion 1 x 1045
Quindecillion 1 x 1048
Sexdecillion 1 x 1051
Septendecillion 1 x 1054
Octodecillion 1 x 1057
Novemdecillion 1 x 1060
Vigintillion 1 x 1063
Unvigintillion 1 x 1066
Duovigintillion 1 x 1069
Trevigintillion 1 x 1072
Quattuorvigintillion 1 x 1075
Quinvigintillion 1 x 1078
Sexvigintillion 1 x 1081
Septenvigintillion 1 x 1084
Octovigintillion 1 x 1087
Nonvigintillion 1 x 1090
Trigintillion 1 x 1093
Untrigintillion 1 x 1096
Duotrigintillion 1 x 1099
Ten-duotrigintillion (or Googol) 1 x 10100
Skewer’s Number 1 x 10130
Centillion 1 x 10303
Googolplex 1 x 1010100