In each of the questions given below four words are given in bold. These four words may or may not be in their correct position. The sentence is then followed by options with the correct combination of words that should replace each other in order to make the sentence grammatically and contextually correct. Find the correct combination of the words that should interchange. If the sentence is correct as it is then, select option “No interchange required” as your choice.

After having (A) the stress seemed (B) on a president, witnessing (C) access to a personal chef placed (D) to be the best perk of the job.

To find the correct combination of words that need to be interchanged, let us analyze the sentence and check the contextual and grammatical fit of the words in bold:

The original sentence is: "After having (A) the stress seemed (B) on a president, witnessing (C) access to a personal chef placed (D) to be the best perk of the job."

Let us evaluate the positions of the words:
1. "After having the stress..." does not fit well when followed by "seemed on a president". Instead, one witnesses stress. Swapping having (A) with witnessing (C) gives "After witnessing the stress...". This is contextually correct.
2. "the stress seemed on a president..." is grammatically incorrect. Stress is "placed" on someone. Swapping seemed (B) with placed (D) gives "the stress placed on a president". This makes perfect sense.
3. In the second part of the sentence, swapping A and C gives "...having access to a personal chef...". This is grammatically correct as "having access" acts as the gerund subject.
4. Swapping B and D gives "...seemed to be the best perk of the job." The verb "seemed" perfectly fits before the infinitive "to be".

Putting it all together with the interchanges A-C and B-D, we get:
"After witnessing (C) the stress placed (D) on a president, having (A) access to a personal chef seemed (B) to be the best perk of the job."

This sentence is grammatically and contextually correct. Therefore, the correct combination to interchange is A-C & B-D.