Examples of chemicals produced by plants as a defense against grazers and browsers
`{:(I.,"Nicotine",II.,"Caffeine"),(III.,"Quinine",IV.,"Strychnine"),(V.,"Opium","",""):}`
Choose the correct combination

Options

A. I and II
B. I,II,III and IV
C. I,II and III
D. I,II ,III ,IV and V

Answer

To solve the question regarding the examples of chemicals produced by plants as a defense against grazers and browsers, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for examples of chemicals that plants produce to defend themselves from animals that graze on them (grazers) or browse on their leaves (browsers).

2. **Identify the Chemicals**: The chemicals listed in the question are:
- Nicotine
- Caffeine
- Quinine
- Strychnine
- Opium

3. **Research Each Chemical**:
- **Nicotine**: A toxic alkaloid found in tobacco plants, which deters herbivores due to its toxicity.
- **Caffeine**: Found in coffee and tea plants, it can act as a deterrent to some insects and herbivores.
- **Quinine**: Known for its use in tonic water, it is derived from the cinchona tree and has insect-repelling properties.
- **Strychnine**: A highly toxic alkaloid that can deter animals from consuming the plant.
- **Opium**: Derived from the poppy plant, it has narcotic properties that can deter herbivores.

4. **Determine the Correct Combination**: All the listed chemicals are known to be produced by plants as a defense mechanism against grazers and browsers. Therefore, they all qualify as examples of defensive chemicals.

5. **Select the Answer**: Since all options (I, II, III, IV, and V) are valid examples of plant defense chemicals, the correct combination includes all of them.

### Final Answer:
The correct combination of chemicals produced by plants as a defense against grazers and browsers is:
- Nicotine
- Caffeine
- Quinine
- Strychnine
- Opium