The correct option is B 6,000 km
The Great Rift Valley is a series of contiguous geographic trenches, approximately 6,000 kilometres (3,700 mi) in total length, that runs from the Beqaa Valley in Lebanon in Asia to Mozambique in southeastern Africa.[1] While the name continues in some usages, it is rarely used in Geology nowadays as it is considered an imprecise merging of separate though related rift and fault systems.