A phospholipid molecule has a head and two tails. The tails are found :

Options

A. at the surfaces of the membrane
B. in the interior of the membrane
C. spanning the membrane
D. where the environment is hydrophilic

Explanation

**Step-by-Step Solution:**

1. **Understanding Phospholipid Structure**: A phospholipid molecule consists of a hydrophilic (water-loving) head and two hydrophobic (water-fearing) tails. This unique structure is crucial for forming cellular membranes.

2. **Identifying the Location of the Head**: The hydrophilic head of the phospholipid is attracted to water, which means it will be located on the surfaces of the membrane where it can interact with the aqueous environment.

3. **Identifying the Location of the Tails**: The hydrophobic tails, on the other hand, do not interact favorably with water. Therefore, they are oriented towards the interior of the membrane, away from the water.

4. **Conclusion**: Since the question asks where the tails are found, the correct answer is that the tails are located in the interior of the membrane.

5. **Reviewing Incorrect Options**:
- "At the surfaces of the membrane" is incorrect because that is where the hydrophilic heads are located.
- "Spanning the membrane" is incorrect as this refers to transmembrane proteins that pass through the membrane.
- "Where the environment is hydrophilic" is also incorrect since the tails are hydrophobic and prefer to be in a non-aqueous environment.

**Final Answer**: The tails of a phospholipid molecule are found in the interior of the membrane.

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