Endocrine glands are those glands which pour their secretion directly into

Options

A. Ducts
B. Substrate
C. Blood
D. All of the above

Explanation

### Step-by-Step Text Solution:

1. **Understanding Endocrine Glands**: Endocrine glands are specialized glands in the body that secrete hormones directly into the bloodstream rather than through ducts.

2. **Identifying the Options**: The question provides four options:
- A) Ducts
- B) Substrate
- C) Blood
- D) All of the above

3. **Analyzing Each Option**:
- **Option A: Ducts**: This option is incorrect because endocrine glands do not use ducts to release their secretions. Instead, they are ductless.
- **Option B: Substrate**: This option is also incorrect. Substrate does not refer to a medium through which hormones are secreted by endocrine glands.
- **Option C: Blood**: This is the correct option. Endocrine glands release their hormones directly into the bloodstream, which then transports these hormones to target organs or tissues.
- **Option D: All of the above**: This option is incorrect since not all the previous options are correct.

4. **Conclusion**: The correct answer to the question is **C) Blood**. Endocrine glands are ductless and pour their secretions directly into the blood.