Which of the following is a characteristic of accumulative pesticides?

Accumulative pesticides are defined by their ability to persist and accumulate in the tissues of living organisms over time. This characteristic means that these pesticides do not break down quickly in the environment or within organisms, leading to a gradual build-up that can have harmful long-term effects. When organisms, particularly those higher up the food chain, consume prey that has absorbed these chemicals, the concentration of the pesticide can increase in their bodies through a process known as bioaccumulation.

The other options do not align with this characteristic. Quick decomposition in the environment suggests that the pesticide would not have a lasting impact, which is contrary to the definition of accumulative pesticides. Similarly, being easily washed away indicates a lack of persistence, which again does not fit with the concept of accumulation. Lastly, causing immediate effects only means that the impacts of the pesticide are short-lived and do not involve long-term accumulation, confirming that the correct choice reflects a fundamental aspect of these substances.