The acylating species in the Friedel-Crafts acylation of benzene to give acetophenone is (a) \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{O}^{\odot}\) (b) \(\mathrm{AlCl}_{4}\) (c) \(\mathrm{CH}_{3}-\stackrel{\oplus}{\mathrm{C}}=\ddot{\mathrm{O}}\) (d) \(\mathrm{CH}_{3}^{-\mathrm{C} \mathrm{C} \mathrm{Cl}}-\mathrm{O}-\mathrm{AlCl}\)

Friedel-Crafts acylation is an electrophilic aromatic substitution reaction that involves the reaction of an acyl chloride with an aromatic compound, typically benzene. This reaction occurs in the presence of a Lewis acid catalyst, such as aluminum chloride (AlCl3). The general mechanism involves the formation of an acylium ion (RC=O^+), which acts as the electrophile and attacks the aromatic ring.

Now we will analyze each of the given options and compare them to the expected structure of the acylating species in Friedel-Crafts acylation: (a) \(\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{O}^{\odot}\): This is an isoelectronic species and not the correct structure for an acylating species. (b) \(\mathrm{AlCl}_{4}\): This option is actually the structure of aluminum chloride (AlCl3) with an extra Cl. Although aluminum chloride commonly acts as a catalyst in the Friedel-Crafts acylation, it is not the acylating species. (c) \(\mathrm{CH}_{3}-\stackrel{\oplus}{\mathrm{C}}=\ddot{\mathrm{O}}\): This is an acylium ion with a positive charge on the carbon atom, which makes it a good electrophile. This structure aligns with the expected structure of the acylating species in Friedel-Crafts acylation. (d) $\mathrm{CH}_{3}^{-\mathrm{C} \mathrm{C} \mathrm{Cl}}-\mathrm{O}-\mathrm{AlCl}$: This option does not represent the correct structure for an acylating species.

Based on the analysis of the given options, option (c) \(\mathrm{CH}_{3}-\stackrel{\oplus}{\mathrm{C}}=\ddot{\mathrm{O}}\) is the correct structure for the acylating species in the Friedel-Crafts acylation of benzene to give acetophenone. This species is an acylium ion and carries the required electrophilic properties for the reaction.