The first blank is about expressing doubt, and the second blank is about Kayode's action after the alleged theft.

Option A ("should not/driving") doesn't fit because "should not" implies a recommendation or advice, and it doesn't convey doubt.

Option B ("should not/drive") is also incorrect because it doesn't convey doubt, and "drive" would not be suitable after "saw him."

Option C ("cannot/drive") is grammatically incorrect. Though,  "Cannot" expresses doubt about the truth of the statement, "drive" is inappropriate after "saw him."

Option D ("cannot/driving") is the correct choice. After "saw him," the correct form is "driving" because he was seen while he was driving the car.

So, the completed sentence is: "I heard that Kayode's car was stolen last night. It cannot be true because I saw him driving it, this morning."