This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable & Non Communicable Disease, Subject name: Social & Preventive Medicine
Which of the following are included in Malaria Vector Indices in pre-eradication era ? a)Spleen ratio b)Human blood index c) Slide positivity rate d)Parasite density index 
Select and explain. 
A. 1,3, B. 1,4, C. 1, 2, 3, D. 4,3,1
B: 1,4
Answer: B: 1,4 
Explanation: Malaria vector indices are divided into 3 groups. 1.Pre-eradication era 2.Eradication ERA 3. Malaria vector indices Spleen ratio AV. Enlarged spleen Parasite rate Parasite density index IPR PCR API ABER AFI SPR SFR Human blood index Sporozoite rate Mosquito Density Biting density Inoculation rate