Given the declarations below, write the statements to combine the person$$s full name and store it into the full string variable.

string first $=$ "First";

string middle $=$ "Middle";

string last $=$ "Last";

string space $=""$;

string full $=""$;

a$.$

full $=$ first $+$ middle last;

b$.$

full $=$ first $+$ space $+$ middle $+$ space $+$ last;

c$.$

full $=$ first $||$ space $||$ middle $||$ space $||$ last;

d$.$

replace $($full$,$ first, middle, last$)$;