Pick the odd one out with regard to digestive juices.
Mouth, stomach, oesophagus, duodenum,

Explanation

To solve the question of which option is the odd one out with regard to digestive juices, we can analyze each option step by step.

### Step 1: Analyze the Mouth
- The mouth is involved in the initial stage of digestion.
- It secretes digestive juices, primarily saliva, which contains the enzyme salivary amylase.
- Salivary amylase helps in breaking down carbohydrates.

**Hint:** Think about the role of saliva in digestion.
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