C, d,f, g,k, o, what letter would complete this list?

you could deduce the conclusion directly using the facts pertaining to the specific situation.

hope this .

answer: 4  

the square root of 16 is 4. it is a very simple mathematic concept. a square root when a number multiplied by itself will result in a number. here, the number 16 comes when 4 is multiplied by 4. hence the square root of 16 is 4. you can always figure out a square root by the inverse operation of squaring.