Which of the Following Is Most Likely to Be a Finding

Which of the following is most likely to be a finding from a normative investigation?

A) Shyness is a personality trait that is relatively stable over time.
B) Children must have a rudimentary understanding of symbolism before they can learn to read.
C) The average child can build a tower of three blocks at the age of 18 months.
D) Attempts at toilet training are futile until the child has voluntary control of the necessary muscles.