1. Principle involved: acid-catalyzed dehydration of alcohols
   Under acidic conditions, alcohols lose water to form alkenes. The ease of dehydration depends mainly on the stability of the intermediate/cation-like transition state and on whether the product alkene is especially stabilized.

2. Key idea for $\beta$-hydroxy carbonyl compounds
   Compounds containing the pattern $\ce{-CO-CH(OH)-}$ or, more generally, a $\beta$-hydroxy carbonyl system, dehydrate very easily under acidic conditions because they give an $\alpha,\beta$-unsaturated carbonyl compound, which is strongly stabilized by conjugation.

3. Examine each option

   Option A: 1-Pentanol

   Structure: $\ce{CH3-CH2-CH2-CH2-CH2OH}$ This is a simple primary alcohol. Its dehydration requires harsher conditions because it does not gain any special stabilization in the alkene product.

   So, not the most readily dehydrated.

   Option B: 4-Hydroxypentan-2-one

   Structure: $\ce{CH3-CO-CH2-CH(OH)-CH3}$ Here the $\ce{OH}$ is at the $\gamma$-position relative to the carbonyl, not the $\beta$-position. Dehydration would not directly give a conjugated $\alpha,\beta$-unsaturated ketone in the most straightforward way.

   Hence, it is not especially activated for easy dehydration.

   Option C: 3-Hydroxypentan-2-one

   Structure: $\ce{CH3-CO-CH(OH)-CH2-CH3}$ Here the $\ce{OH}$ is on the $\beta$-carbon relative to the carbonyl group. This is a $\beta$-hydroxy ketone. On dehydration, it forms: $\ce{CH3-CO-CH=CH-CH3}$ which is an $\alpha,\beta$-unsaturated ketone, stabilized by conjugation.

   Therefore, this compound dehydrates very readily under acidic conditions.

   Option D: 2-Hydroxycyclopentanone

   This is also an $\alpha$-hydroxy ketone (the $\ce{OH}$ is adjacent to the carbonyl). Dehydration here would not be as straightforward/favorable as in a $\beta$-hydroxy carbonyl leading to a conjugated enone.

   So, it is less readily dehydrated than option C.

4. Conclusion
   The compound that most readily undergoes dehydration is the one that forms a conjugated enone most directly, i.e. 3-hydroxypentan-2-one.

$\boxed{\text{Option C}}$

5. Comparison with stored answer
   Stored correct answer: B
   Derived answer: C

   These do not match. The likely reason is that option C is the true $\beta$-hydroxy ketone, which dehydrates most easily to an $\alpha,\beta$-unsaturated ketone. Option B is a $\gamma$-hydroxy ketone and does not enjoy the same direct conjugation-driven dehydration advantage.