The glands present in the skin of frog are

Options

A. (a) Sweat and mammary glands
B. (b) Sweat and sebaceous glands
C. (c) Sweat and mucous glands
D. (d) Mucous and poisonous glands .

Answer

### Step-by-Step Solution:

1. **Identify the Type of Animal**: Frogs belong to the class Amphibia, which includes animals that are both terrestrial and aquatic.

2. **Understand the Skin Structure**: The skin of frogs is moist and plays a crucial role in their respiration and protection.

3. **Identify the Glands in Frog Skin**:
- **Granular Glands**: These glands secrete a poisonous substance that serves as a defense mechanism against predators. They are often referred to as poisonous glands.
- **Mucous Glands**: These glands secrete mucus, which keeps the skin moist and aids in respiration through the skin.
- **Seromucous Glands**: These are modified mucous glands that also contribute to the moisture of the skin.

4. **Evaluate the Options**:
- **Option A**: Sweat and mammary glands - Incorrect, as these are not present in frogs.
- **Option B**: Sweat and sebaceous glands - Incorrect, as frogs do not have these glands.
- **Option C**: Sweat and mucus - Incorrect, as sweat glands are not present, but mucus glands are.
- **Option D**: Mucus and poisonous - Correct, as both mucous glands and granular (poisonous) glands are present in frog skin.

5. **Conclusion**: The correct answer is **Option D**: Mucus and poisonous glands.