-  The first and last letter remain unchanged, while the second and second last, third and third last letter and so on are interchanged, to obtain the code.

The given code for "PEOPLE" is "PLPOEE". We can observe that the code for each letter is made up of a pair of letters:

• The first letter of each pair is the original letter in the word.
• The second letter of each pair is the next letter in the word.

Using this logic, we can determine the code for "TREND" as follows:

• The first letter is "T", so the first letter of the code is "T".
• The next letter after "T" in the word "TREND" is "N", so the second letter of the code is "N".
• The next letter after "N" in the word "TREND" is "E", so the third and fourth letters of the code are "E".
• The next letter after "E" in the word "TREND" is "R", so the fifth letter of the code is "R".
• The next letter after "R" in the word "TREND" is "D", so the sixth letter of the code is "D".

Therefore, the code for "TREND" is "TNERD", which is option E.

In summary, we can use the following formula to determine the code for a given word:

• For each letter in the word, take the original letter followed by the next letter in the word.
• Combine all pairs of letters to form the code for the word.