Final answer:
New Imperialism led to deforestation, brutal labor conditions, and the suppression of local religious beliefs. Option D, regarding Western medicines, offers a contrasting positive effect amidst the overall negative impacts.
Step-by-step explanation:
Negative Impacts of New Imperialism on Colonial Holdings
During the era of New Imperialism, numerous negative effects were inflicted upon colonial holdings. Firstly, A. The removal of resources such as rubber and the construction of infrastructure like railroads often led to significant deforestation and environmental degradation. Secondly, B. Natives experienced brutal living conditions as they were forced into labor, with many working in semi-slavery or worse to meet the demands of the colonizing countries. Thirdly, C. The suppression of local religious beliefs and practices occurred as imperial powers pushed for the adoption of Christian faiths.
However, one should note that option D. does not represent a negative impact as it discusses the introduction of Western medicines and vaccines that decreased the occurrence of diseases, which can be seen as a positive outcome amidst the many adverse repercussions of imperialism.