Arrange the events in chronological order:

(A) China occupies Aksai-Chin area

(B) Full diplomatic relations were restored between India and China

(C) Atal Behari Vajpayee the first top level leader to visit China

(D) China’s massive invasion

The correct option is (A), (D), (B), (C).

To arrange these historical events in chronological order, we examine the date of occurrence for each event:

(A) China occupies Aksai-Chin area: During the mid-to-late 1950s, China began constructing a military road through the Aksai Chin region (linking Tibet and Xinjiang) and gradually established control over the area, which became a major flashpoint by 1957–1959.

(D) China’s massive invasion: This refers to the Sino-Indian War, which began with a massive military invasion by China on October 20, 1962.

(B) Full diplomatic relations were restored between India and China: Following the 1962 war, diplomatic ties were severely downgraded. Full diplomatic relations (at the ambassadorial level) were restored in the year 1976.

(C) Atal Behari Vajpayee the first top level leader to visit China: Atal Bihari Vajpayee, serving as India's Minister of External Affairs, visited China in February 1979, marking the first top-level visit from India to China since the 1962 conflict.

Therefore, the chronological sequence of the events is (A) → (D) → (B) → (C).