Choose the fraction that has not been reduced to simplest form. 10/19 15/16 19/38 21/34

The answer for this question would be C) 19/38 or the third option since its not to its simplest form because we can still simplify this fraction and this how:

lets first find the GCF of 19 and 38 and that would be 19
second divide both 19 and 38 by the GCF 
lastly simplify it and the simplest form of 19/38 would be 1/2