Look at the photograph.

A river ending in a waterfall.

The photograph best supports which detail from Into the Unknown by Stewart Ross?

David Livingstone made the first recorded east-west journey across Africa.
David Livingstone was the first Westerner to see Victoria Falls, which he named after Queen Victoria.
The Zambezi River turned out to be shallower than David Livingstone had anticipated.
The crew faced many challenges such as extreme heat, malaria, and cockroaches.