The correct option is diacritical marks and respelling.
Explanation:
On one hand, a pronunciation respelling is a notation used in the English language to convey the pronunciation of words. On the other hand, a diacritical mark, also known as the accent mark, is a symbol added to a letter that alters its sense or pronunciation, indicating as well its appropriate stress.
Bearing the above in mind, it could be said that the dictionary feature that helps to pronounce a word is diacritical marks and respelling.
I think it is accent marks and re-spelling because they always have accent marks when they are trying to help you pronounce the word and they help you recognize what letters to pronounce how to pronounce them.
C) Celebrate. This would make better sense, since it isn't having a claim to recognize something when it already is a holiday. Observing something would simply be to inspect. Mark is definitely not your answer and you should know that the last ones available aren't reasonable! So the answer is C)
