If a State administration takes adequate measures to kill mosquito larvae and adult mosquitoes, it is likely to lead to a decline in the number of diseases spread by mosquitoes.

Option 1: Chikungunya is a viral disease transmitted by the Aedes mosquito. Adequate measures to kill the mosquitoes would reduce their population and therefore, the transmission of the Chikungunya virus. So, Chikungunya would likely decline in numbers.

Option 2: Filaria, also known as lymphatic filariasis, is a parasitic disease transmitted by mosquito species like Culex. If measures are taken to kill the mosquitoes, the transmission of the filarial parasite would be reduced, leading to a decline in the number of filaria cases. Therefore, Filaria would likely decline in numbers.

Option 3: Japanese encephalitis is a viral disease transmitted by the Culex mosquito. If the State administration takes measures to kill the mosquitoes, it would reduce the transmission of the virus and ultimately lead to a decline in Japanese encephalitis cases. Therefore, Japanese encephalitis would likely decline in numbers.

Option 4: Kalazar, also known as visceral leishmaniasis, is a parasitic disease transmitted by sandflies,