The correct answer is (d).
A word is said to be symmetrical if it looks the same when reflected in a mirror. In other words, if you write the word on a piece of paper and then fold the paper in half so that the word lines up with itself, the two halves should be identical.
Of the four words given, only AMUMA is symmetrical. This is because all of the letters in AMUMA are the same, and they are all in the same order. When you reflect AMUMA in a mirror, the two halves of the word are identical.
The other three words are not symmetrical. In AXNXA, the X’s are not in the same order on either side of the mirror. In CLOLC, the C’s are not in the same order on either side of the mirror. And in AOMDE, the O’s are not in the same order on either side of the mirror.
Therefore, the correct answer is (d).