Bioassay is the correct answer.

Explanation:
Bioassay is a technique used to determine the biological activity or potency of a substance by measuring its effect on a living organism or tissue. It involves the use of a living material, such as a plant or plant part, to test the substance for its growth response or other biological effects.

Bioassays are commonly used in various fields of research and industry, including pharmacology, toxicology, agriculture, and environmental science. They are particularly useful in evaluating the effectiveness and safety of drugs, pesticides, and other chemicals.

Advantages of Bioassay:
1. Specificity: Bioassays provide a direct measure of the biological activity of a substance, which is often more relevant and specific than other methods.
2. Whole organism response: By using a living organism or tissue, bioassays can capture the complex interactions and responses that may not be observed in isolated cell or tissue culture experiments.
3. Predictive value: Bioassays can provide valuable information about the potential effects of a substance in a real-life scenario, allowing for better prediction of its impact on living organisms.

Steps in a Bioassay:
1. Selection of test organism: The choice of a suitable organism or tissue depends on the specific purpose of the bioassay and the characteristics of the substance being tested.
2. Preparation of samples: The substance to be tested is typically prepared in different concentrations or dilutions to assess its dose-response relationship.
3. Exposure of the organism: The test organism or tissue is exposed to the different concentrations of the substance, either by direct application or through a controlled environment.
4. Measurement of response: The biological response of the organism, such as growth, survival, enzyme activity, or physiological changes, is measured and compared among the different concentrations of the substance.
5. Statistical analysis: The data obtained from the bioassay is analyzed using appropriate statistical methods to determine the potency or effectiveness of the substance.

In conclusion, bioassays are valuable tools for evaluating the biological activity of substances using living materials like plants or plant parts. They provide important information for various scientific and practical applications, helping to ensure the safety and effectiveness of pharmaceuticals, pesticides, and other chemicals.