on a corpse, there are beetles, cockroaches, and ants, which is the correct PMI?

Postmortem Interval (days) | insects present
------------------------------------------------|-----------------------------------
0-3 | blowflies
4-7 | fly larvae and beetles
8-18 | ants, cockroaches, beetles, and flies
19-30 | beetles and mites
31+ | none

a) 8-18 days
b) 0-3 days
c) 19-30 days
d) 4-7 days

Postmortem interval is defined as the time elapsed since the person died.In order to estimate the time since death experts carefully studies the breeding of insects on the dead body of the person .

According to question , on a corpse there are beetles , cockroaches and ants.

According to table given ,:

Beetles arrives on the dead body at forth day from the time of death.
Ants and cockroaches arrives on the dead body at eighth day from the time of death.

The correct PMI is 8 - 18 days because beetles, ants and cockroaches all are present on a corpse.

Hence ,correct answer is option A.