Which one of the following statements cannot be connected to Predation?

While explaining interspecific interaction of population, (+) sign is assigned for beneficial interaction, ($$-$$) sign is assigned for detrimental interaction and (0) for neutral interaction. Which of the following interactions can be assigned (+) for one specifies and ($$-$$) for another specifies involved in the interaction?

If '8' Drosophila in a laboratory population of '80' died during a week, the death rate in the population is ___________ individuals per Drosophila per week.