Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 31 to 35.

The main idea behind ecotourism is to educate tourists about conservation efforts and research developments in fragile natural areas, while also offering travelers a chance to experience those areas firsthand. Unfortunately, when those fragile areas start to receive a lot of traffic from tourists, it can negatively impact their ecosystems.

Tourism inevitably leads to development – even in ecotourism efforts. When natural areas become popular in the travel industry, they usually become the site of hotels, excavations and other tourist industry activities. These activities sometimes displace indigenous groups and local people from their homelands, which not only damages the integrity of those local communities, but prevents its members from benefiting from the economic benefits of a growing tourism industry.

On top of ecotourism’s potential impacts on locals, the industry can also take a toll on surrounding wildlife. It’s ironic, given that ecotourism aims to educate ecotourists and promote the conservation of natural habitats, but, for some species, the increased presence of humans may by default negatively impact their natural behaviors. Increased foot traffic can also affect soil quality and plant life in general, damaging the area’s overall ecosystem.

Finally, not all travel organizations that market themselves as ecotourist programs are actually environmentally friendly. These organizations know ecotourism is growing in popularity and may take advantage of that fact by parading as ecotouristic when in reality they ignore eco-friendly practices. For that reason, it’s important that would-be ecotourists do their homework before giving an organization their business.

(Adapted from https://traveltips.usatoday.com/)

What does the author mean when suggesting that ecotourists should “do their homework”?