What environmental factor does NOT contribute to malaria transmission?

The choice that indicates temperature fluctuations do not contribute to malaria transmission is based on the fact that temperature is indeed a critical factor influencing the life cycle of both malaria parasites and their mosquito vectors.

During certain temperature ranges, the development rate of malaria parasites within the mosquito increases, and warmer temperatures can enhance mosquito breeding and survival rates. Higher temperatures can also affect the biting frequency of mosquitoes and the longevity of the vectors, hence playing a significant role in malaria transmission dynamics.

In contrast, the other options are directly related to the transmission process. Rainfall patterns, for example, create suitable habitats for mosquito breeding in stagnant water, and the proximity of breeding sites to human settlements determines how easily mosquitoes can access human hosts. The distribution of mosquito species is crucial as only specific types of mosquitoes are capable of transmitting the malaria parasite.

Overall, it is clear that while temperature fluctuations do influence malaria dynamics, they cannot be dismissed as non-contributory to transmission, unlike the selected answer.