The correct answer is: A. Nitric acid and acetic anhydride.
Nitro groups are typically introduced into aromatic rings by the action of nitric acid. In the presence of a dehydrating agent such as acetic anhydride, the nitric acid is protonated to form nitric acidium nitrate, which is a more reactive electrophile. This electrophile then attacks the aromatic ring, resulting in the formation of a nitro group.
The reaction of nitric acid with anthracene in the presence of acetic anhydride is shown below.
$$\ce{C14H10 + HNO3 + Ac2O -> C14H9NO2 + H2O + AcOH}$$
The product of this reaction is 9-nitroanthracene.
The other options are incorrect because they do not involve the use of a dehydrating agent. In the absence of a dehydrating agent, the nitric acid is not as reactive and the reaction is not as efficient. This results in the formation of a mixture of products, including 9-nitroanthracene, 1-nitroanthracene, and 2-nitroanthracene.
Nitric acid and ethyl alcohol can be used to nitrate aromatic rings, but the reaction is not as efficient as the reaction with acetic anhydride. This is because ethyl alcohol is not a strong enough dehydrating agent.
Nitric acid and acetic acid can also be used to nitrate aromatic rings, but the reaction is even less efficient than the reaction with ethyl alcohol. This is because acetic acid is not a strong enough dehydrating agent and it also competes with the aromatic ring for the nitric acid.
Nitric acid in excess can also be used to nitrate aromatic rings, but the reaction is not as selective as the reaction with acetic anhydride. This is because nitric acid in excess can nitrate both the aromatic ring and the side chains.