Answer:
Present perfect continuous tense is used for an action which began at some time in the past and is still continuing. It is also used for an action which happened in the past, and whose effect is felt in the present. It is made of two elements: (1) the present perfect form of the verb, 'to be' (have/ has been) and (2) the present participle of the main verb (____+ing).
In the given sentence, the action (work) started in the past (since morning) and is continuing. We know it is continuing because of the clause, 'now she wants to take rest'. This clause also indicates the effect/ result of the action. Hence, this is in present perfect continuous tense.
The subject (She) is a singular noun in the third person. Hence, the present perfect form of the verb, 'to be' is 'has been'. The main verb is 'work', whose present participle form is 'working'. Hence the correct answer is option A.
Option B is grammatically incorrect as the word 'had' (past perfect form of the verb-to be) is used along with 'working' without the word 'been'.
Option C is incorrect as it is in past continuous tense.
Option D is incorrect as it is in past perfect tense.