a)

'\n': This is a character constant representing a newline character. It contains one character.  In each case, the length() method is used to determine the number of characters in the constant.

System.out.println("a. Length: " + String.valueOf('\n').length());

The output of the  '\n'​​​​​​​  length is 1.

b)

'n': This is a character constant representing the letter 'n'. It contains one character.

System.out.println("b. Length: " + String.valueOf('n').length());

The output of the 'n' length is 1.

c)

. "Mary": This is a string constant containing the characters 'M', 'a', 'r', and 'y'. It contains four characters.

System.out.println("c. Length: " + "Mary".length());

The output of the "Mary" length is 4.

d)

"M": This is a string constant containing the character 'M'. It contains one character.

System.out.println("d. Length: " + "M".length());

The output of the  "M" length is 1.

e)

"Mary\n": This is a string constant containing the characters 'M', 'a', 'r', 'y', and a newline character. It contains five characters.

System.out.println("e. Length: " + "Mary\n".length());

The output of the '"Mary\n" length is 5.