Question 81reads:
Typical 4in by 4in ceramic tiles used as wallcovering in an office building's restrooms should be specified as:
a. vitreous
b. semivitreous
c. nonvitreous
d. impervious
Ballast notes the correct answer to be "a. vitreous." however, according to the ballast text, pg. 43-5, it says impervious is the least absorptive of the 4 options. anyone know why the best answer would not be "d. impervious?" cost?
Thanks,