A. Square of all integers is 0 or greater than 0 and there exists an s for which Q(s) is true. Yes there exist such s - 2 &3. Hence this is true.
B. Square of all integers of 0 or greater than 0 and all such integers are solution of equation represented by Q(s). Because solutions of the equation is only 2 & 3. Hence false.
C. Every t is a equal to all non negative integers which are complete square. False as It is for one only. E.g Let s = 2². Now t = 2² for only 2², it can't be equal to s = 3² for obvious reasons.