The global focus on South Asia sharply increased when both India and Pakistan became nuclear powers in 1998. India first tested nuclear weapons in May 1998, followed by Pakistan later in the same month. This development shifted global attention to the region due to concerns over nuclear proliferation and the potential for conflict between these two nuclear-armed neighbors.
Although other events, such as the Kargil conflict (1999) and the Bangladesh War of 1971, were significant, the nuclear tests by India and Pakistan in 1998 were the most pivotal in terms of global focus.
Thus, the correct answer is (C) India and Pakistan both became nuclear power.