Step 1: Understand malaria.
Malaria is a disease caused by the Plasmodium parasite, which is transmitted through the bite of infected Anopheles mosquitoes.
Step 2: Review the options.
- Plasmodium is the correct pathogen responsible for causing malaria.
- Wuchereria causes filariasis, not malaria.
- Sacromyces is a genus of yeast, not related to malaria.
- Puccinia is a genus of fungi that causes wheat rust, unrelated to malaria.
Step 3: Conclude.
Plasmodium is the causative agent of malaria, making option (A) the correct answer.
Final Answer:
\[
\boxed{\text{Plasmodium}}
\]