mentions unpaid work being offered as part of a trip?

Analysis:

The task is to find a reader who describes an opportunity for unpaid work as part of their travel experience.

Answer:

• Reader B states, 'There's also an impressive selection of volunteer projects involving animals, particularly around the country's biggest parks. I spent four weeks helping at a veterinary practice with African Conservation Experience.' This clearly describes unpaid work as part of their experience.

Answer: B