The purpose of collecting evidence in the room where a corpse was found is to
a.) identify the victim and establish a motive for the crime
b.) develop control evidence which can be used to identify the suspect
c.) use the evidence to identify links which will eventually reconstruct how the person died, that is, identify links in such a way that it will stand up in court
d.)establish links which will identify the suspect

C.) use the evidence to identify links which will eventually help reconstruct how the person died, that is, identify links in such a way that it will stand up in court.

When it comes to evidence collection, especially in the room where a corpse was found, the evidence around the room can give the investigators  clues on how the person died. This is especially important when investigating a crime where no witnesses are available.

The investigators then have a chance to find out the story of how the victim died by the evidence around the room such as blood spatter, messed up things, deadly or possible weapons, etc. By having learned about the different evidence collected, the investigators may use the evidence found in court.

C.) use the evidence to identify links which will eventually help reconstruct how the person died, that is, identify links in such a way that it will stand up in court

the answer to your question is sperm

on island x the species needed to adapt because they were being subject to predators which didn't inhabit island y.