The correct option is A her cousin had got 85 marks in the test and her mother would be angry
When a sentence is changed from direct to indirect speech, the subject
pronoun, verbs and tense forms also change. (This is because the speech is reported by someone else, and the tense
of the direct speech goes one tense back as it's spoken at a later time
now.) The meaning of the sentence
should not be changed.
When
the direct speech is in present perfect tense, the reported speech will
change to its past equivalent, past perfect tense. This applies to most
other tenses.
Option A: This sentence is the correct narration of the direct speech, the pronoun 'my' is now 'her' and the present perfect tense verb 'has' is changed to past perfect 'had'. Also, 'will' changes to its past tense form 'would' in indirect speech.
Hence A is correct.
Option B is incorrect because the words 'in the test' are missing. Also, the pronoun 'my' in "my mother" has not been altered.
Option C is incorrect because B does not display the correct reported speech.
D is incorrect as the answer lies in A.