If the first and third letters in the word NECESSARY are interchanged, the fourth and sixth letters are interchanged, and the seventh and ninth letters are interchanged, then which of the following will be the seventh letter from the left in the new word?

Introduction / Context:
Letter interchange questions are a standard type of alphabet test. They examine whether a candidate can follow multiple swap instructions accurately and then read off positions in the resulting word. Here, we have to perform three separate exchanges of letters within the word NECESSARY and then identify the seventh letter from the left in the final arrangement. Precision in indexing and swapping is essential to get the correct result.

Given Data / Assumptions:
- Original word: N E C E S S A R Y.
- Interchange positions: first with third, fourth with sixth, and seventh with ninth.
- Position counting is from the left, starting at one.
- We must identify the letter that ends up in the seventh position after all swaps are completed.

Concept / Approach:
The safe approach is to write the word with positions clearly marked, carry out the specified swaps one by one, and then read off the required position. Because the swaps involve different pairs that do not overlap in indices, we can do them sequentially without confusion. Keeping track of the new arrangement after each step avoids mistakes where an already swapped letter is misused in a later step.

Step-by-Step Solution:
Step 1: Label the original letters with positions: 1 N, 2 E, 3 C, 4 E, 5 S, 6 S, 7 A, 8 R, 9 Y. Step 2: Swap the first and third letters. This changes positions 1 and 3, giving C E N E S S A R Y. Step 3: Now swap the fourth and sixth letters of the new word. The letters at positions 4 and 6 are E and S. After swapping, the word becomes C E N S S E A R Y. Step 4: Finally, swap the seventh and ninth letters. The letters at positions 7 and 9 are A and Y. After this swap, the word becomes C E N S S E Y R A. Step 5: Count the letters in the final word from the left. The seventh letter is Y.

Verification / Alternative check:
It is wise to repeat the swaps quickly to confirm. Starting again from NECESSARY, verify that after all three clearly specified swaps, the final arrangement is C E N S S E Y R A. Confirm that positions one through nine are C, E, N, S, S, E, Y, R, A. From this listing, the seventh letter is obviously Y, which matches our previous result and confirms accuracy.

Why Other Options Are Wrong:
- "E" appears in the word but finishes in positions 2 and 6, not in position 7.
- "S" appears in positions 4 and 5 in the final word, not at position 7.
- "R" occupies position 8 after the swaps.
Hence, none of these alternatives satisfies the requirement of being the seventh letter from the left.

Common Pitfalls:
A common error is to misread which positions are being swapped or to forget that the swaps should be applied to the current version of the word, not always to the original one. Another frequent issue is careless counting from the left when identifying final positions. Writing the word clearly after each swap and re numbering positions if necessary greatly reduces the chance of mistakes in similar letter manipulation problems.

Final Answer:
After performing all the specified interchanges, the seventh letter from the left is Y.