Explanation:

- Both cars X and Y start at 8 a.m. from places A and B, 800 km apart.

- Car X drives at 50 km/h but stops after 1 hour at 9 a.m., having covered 50 km.

- Car X resumes at 10 a.m. from the 50 km mark.

- Car Y moves continuously without stopping at 50 km/h.

- By 10 a.m., Car Y has covered 100 km (2 hours * 50 km/h).

- At 10 a.m., the distance between X and Y is 650 km.

- Both cars now move towards each other at a combined speed of 100 km/h.

- They take 6.5 hours to cover the remaining 650 km (650 km / 100 km/h).

- The cars meet at 4:30 p.m. (10 a.m. + 6.5 hours).

- Answer: 2, 4:30 p.m.

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