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2(d). Which of the following statements are invalid? Select all that apply (cirele your CHOICEs or write the letters). int sain O ( int var1-5; const int var2 -6: const int. ptr1-varl: int& ref1 -varl; int& ref2 var2: 1 CHOICE A /1 CHOICE B int const ptr2 -avar2: 11 CHOICE C const int ptr3 - var2: I CHOICED /1 CHOICE E Ptri -11: retura o 2(e). Will the following program compile without error? YES NO #include int foo(int& i)t int main) f int a -2; std::cout . (g). List two uses for pass by reference (write at most two sentences). ). List one possible disadvantage of a hash map over a balanced binary search tree