Allyl phenyl ether can be prepared by heating:

To prepare allyl phenyl ether, which has the structure CH2=CH-CH2-O-C6H5, we use the Williamson ether synthesis. This method involves the reaction of an alkoxide ion with an alkyl halide to form an ether. The general reaction is R-ONa + R'-X → R-O-R' + NaX, where R and R' are alkyl or aryl groups.

In this case, allyl phenyl ether has two parts: the allyl group (CH2=CH-CH2-) and the phenyl group (C6H5-). We need to choose the correct combination of reactants from the options.

Let's evaluate each option:

Option A: CH2=CH-Br + C6H5-CH2-ONa
Here, CH2=CH-Br is vinyl bromide. Vinyl halides are unreactive in nucleophilic substitution reactions because the carbon is sp2 hybridized, and the C-Br bond has partial double bond character due to resonance. This makes it difficult for nucleophiles to attack. The product would be CH2=CH-O-CH2-C6H5 (vinyl benzyl ether), not allyl phenyl ether. So, this option is incorrect.

Option B: C6H5-CH=CH-Br + CH3-ONa
Here, C6H5-CH=CH-Br is styryl bromide (a vinyl halide). Vinyl halides are unreactive for the same reasons as in option A. The product would be C6H5-CH=CH-O-CH3 (styryl methyl ether), not allyl phenyl ether. So, this option is incorrect.

Option C: CH2=CH-CH2-Br + C6H5ONa
Here, CH2=CH-CH2-Br is allyl bromide, and C6H5ONa is sodium phenoxide. Allyl bromide is a primary alkyl halide but is highly reactive due to resonance stabilization of the intermediate carbocation in SN1 or the transition state in SN2 reactions. Sodium phenoxide is a strong nucleophile. The reaction proceeds as:
CH2=CH-CH2-Br + C6H5ONa → CH2=CH-CH2-O-C6H5 + NaBr
The product is allyl phenyl ether (CH2=CH-CH2-O-C6H5). This reaction is feasible under heating conditions.

Option D: C6H5Br + CH2=CH-CH2-ONa
Here, C6H5Br is bromobenzene (an aryl halide), and CH2=CH-CH2-ONa is sodium allyloxide. Aryl halides like bromobenzene do not undergo nucleophilic substitution easily under normal heating conditions because the carbon is sp2 hybridized, and the C-Br bond is strong due to resonance. Special conditions (e.g., high temperature and pressure) are required for substitution. The product would be C6H5-O-CH2-CH=CH2 (allyl phenyl ether), but the reaction does not occur readily. So, this option is incorrect.

Therefore, only option C provides a feasible route to synthesize allyl phenyl ether via Williamson ether synthesis.

Hence, the correct answer is Option C.