Key Factors in Malaria Distribution

Steps:

• Identify malaria as a vector-borne disease transmitted by Anopheles mosquitoes, requiring specific environmental conditions.
• Recall that distribution depends on mosquito breeding sites (stagnant water influenced by rainfall) and temperature for parasite lifecycle.
• Evaluate choices: Assume standard factors where 1=temperature, 5=mosquito vector presence; others like 2=soil type, 3=human diet, 4=vegetation cover are less direct.
• Select option matching primary biotic/abiotic drivers: 1 and 5.

Why B is correct:

• Malaria's geographic spread follows the Anopheles mosquito range (factor 5) and optimal temperatures (16–33°C for factor 1), per WHO epidemiology definitions.

Why the others are wrong:

• A includes irrelevant 2 and 4, which do not directly limit parasite or vector survival.
• C omits critical temperature (1) needed for Plasmodium development in mosquitoes.
• D features 3 and 4, secondary or non-causal elements like host immunity or land use.

Not enough information on exact factor labels, but B aligns with core drivers.

Final answer: B