The correct option is
B She was their
As the given sentence in the direct speech is in the simple present tense, we will convert it into the simple past tense.
Instead of 'I', we must use another pronoun according to the name or the subject of the sentence. Here, 'Ms. Neela' is a female and hence we will use 'she' instead of 'I'.
Instead of 'your', we must use another pronoun according to the name or the object of the sentence. Here, 'class' is the plural object and hence we will use 'their' instead of 'your'.
Option A - 'She is your' can't be used here as 'your' has to be replaced with 'their'. Also, 'is' is used to represent a sentence in the simple present tense and we need the sentence in the simple past tense. Thus option A is incorrect.
Option B - 'I am your' is incorrect as 'am' is used to represent the sentence in the simple present tense. Also, 'I' and 'your' can't be used as explained above. Thus option B is incorrect.
Option C - 'She is their' is incorrect as we can't use 'is' as it represents the sentence in the simple present tense. Thus option C is incorrect.
Option D - 'She was their' can be used as 'was' is used to represent a sentence in the simple past tense. Thus option D is the correct answer.
'Ms. Neela told the class that she was their new English teacher.'