Complete the given statement using the appropriate option:
Hello, Tom. I _______ (look) for you all morning. Where have you been?
a) had been looking
b) have been looking
c) have looked
d) is looking

Hint: A verb is a content word that denotes an action, occurrence, or state of existence. A verb is the word class that serves as the predicate of a sentence.

Complete answer:
In the given question, we have to find out which of the given options includes the answer in present perfect continuous tense, as this tense describes an unbroken action continuing at the present time, started in the recent past (looking for Tom).
Let us thus analyze the options given to us in this question -
Option (a.), 'had been looking', refers to past perfect continuous tense.
Therefore, option (a.) is incorrect as the answer should be in the present perfect continuous tense.
Option (b.), ‘have been looking', refers to present perfect continuous tense. Therefore, option (b.) is correct.
Option (c.), ‘have looked', refers to present perfect tense. Therefore, option (c.) is incorrect as the answer should be in the present perfect continuous tense.
Option (d.), ‘is looking', refers to present continuous tense. Therefore, option (d.) is incorrect as the answer should be in the present perfect continuous tense.

Note:
In this question, it will be helpful for the student to recall the concept of tenses. Tense is a grammatical category of verbs used to express distinctions of time. There are three tenses - past, present, and future.