Which of the following must be done before a pesticide can be registered in California?

A comprehensive safety evaluation must be completed before a pesticide can be registered in California because this process ensures that the product is safe for human health and the environment. California has stringent regulations regarding pesticide registration to protect public health, agricultural practices, and the ecosystem. The evaluation involves reviewing data on the pesticide's effectiveness, potential risks to humans and wildlife, and environmental impacts. This thorough assessment is a critical step to ensure that any pesticide used within the state meets safety and efficacy standards established by the Department of Pesticide Regulation (DPR).

In contrast, manufacturing the pesticide within California is not a requirement for registration, as products can be registered regardless of their origin. Popularity among local farmers may suggest market demand, but it does not affect the safety evaluation process or the registration criteria. Advertising in newspapers is not a prerequisite for registration and does not contribute to the evaluation of the pesticide's safety or effectiveness. Hence, only the comprehensive safety evaluation directly relates to the registration process for pesticides in California.