The correct option is
B Could
The word, 'please' in the sentence indicates that it expresses a request. The question mark at the ends of the sentence indicates that this is an interrogative sentence.
Option A:
The auxiliary, 'are' is used along with the present continuous form of the verb. However, in the given sentence, the main verb 'wait' is in simple present tense. Hence, this auxiliary cannot be used. Option B: The modal, 'could' is used in an interrogative sentence to seek permission or to make a request. The sentence, 'Could you please wait for some time?' expresses a request to the listener to wait for some time. Hence, this option is correct.
Option C: The auxiliary, 'have' is used in the formation of perfect tenses. It is used along with the past participle form of the verb. The past participle form of the verb, 'wait' is 'waited', is used in the sentence.
This is also sometimes used to express an obligation. However, the given sentence expresses a request and not an obligation. Hence, this auxiliary cannot be used.
Option D: The auxiliary, 'should' when used in a question seeks an opinion or advice. Eg: 'Should I wait for you?'. However, the given sentence expresses a request and does not seek an opinion or advice. Hence, this auxiliary cannot be used.