In C++, class D inherits from both class B and class C, and both B and C separately inherit from a common base class A (without using virtual inheritance). What problem does this classic "diamond inheritance" arrangement create, and how is it resolved?

Without virtual inheritance, when D inherits from both B and C, and both B and C each separately inherit from A, the resulting object of type D ends up containing two distinct, duplicate copies of A's members — one inherited via the B path and one via the C path — causing ambiguity when code tries to directly access an inherited member of A through D (the compiler cannot determine which copy is intended). This is resolved by declaring B and C's inheritance from A using the "virtual" keyword (e.g., class B : virtual public A), which ensures that only a single, shared copy of A's members exists within any object of type D, regardless of how many inheritance paths lead to it.