Best Answer Explained in Below-:

Prepositions are used to link nouns, phrases or pronouns to other words in a sentence. They are used to indicate the location of the nouns and pronouns.Complete answer:Congratulating means to praise or compliment someone for their achievements.As given in the hint, prepositions modify the given noun or pronoun in a sentence.Example- He swam across the pool. Here, the preposition ‘across’ modifies the position of the noun ‘he’.In the given question: X is congratulating Y on his success. So, here ‘I’ is the subject and ‘you’ is the object.Hence, the correct answer is- I congratulate you on your success. We have used the preposition ‘on’ to indicate an occasion or a subject.Now, let’s look at the given options-- Of- It is used to denote the relationship between two things. Hence, it is an incorrect option.- With- It is generally used with feelings and emotions. Hence, it is an incorrect option.- By- It is used to show the position of the noun in the sentence. Hence, it is an incorrect option.- On- It is used to indicate an occasion or a subject. Hence, it is the correct option.> The correct answer is Option ‘d’.Note: ‘On’ is commonly used in locative context as it indicates the position of an object. But it can also be used to indicate occasions and subjects.