Select the most appropriate option to fill in the blank.

He is the patient ______ called you in the morning.

who

The most appropriate option to fill in the blank is:

☀ who

The sentence would read: "He is the patient who called you in the morning."

Explanation: In this context, "who" is the correct relative pronoun to use to refer to the patient as the subject of the verb "called." The other options don't fit the context:

• Which: This is used for things, not people.

• Whom: This is used as the object of a verb or preposition, and it's not the correct choice here.

• That: While "that" is often used as a relative pronoun, "who" is more appropriate when referring to people.