que--Study the following program written in a block structured language.
var p, q : integer;
begin
p:= p+q;
q:= p−q;
p:= p−q;
end;
(a) exchanges (p) and (q) (b) doubles (p) and stored in (q)
(c) doubles (q) and stores in (p) (d) leaves (p) and (q) unchanged