Which of the following animals did Dahl report seeing during his drive?

The correct answer is elephants, as Roald Dahl describes his experiences vividly during his time in Africa. In "Going Solo," he recounts being on a drive where he encountered wildlife, including elephants, which are significant to his memories of that time. Elephants, with their impressive size and social structures, would have made a remarkable impact on him, contributing to the adventurous and captivating narrative he portrays.

The other animals listed, while they could be present in various African landscapes, are not highlighted in the context of his particular experiences during the drive he describes. Horses are commonly associated with human activity rather than wildlife in this scenario, lions, although iconic to the African savanna, might not be mentioned in this context, and deer, which are not typically found in African regions Dahl was likely exploring, would not fit the setting. Thus, elephants stand out as the correct answer due to their specific mention and relevance to Dahl's experiences.