Concept:The phrasal verb “count on” means to rely on or depend on someone for support or help.Explanation:In this sentence, the speaker wants to express that he has always relied on his friend’s friendship or support.The verb “count” takes the preposition “on” to form this meaning.The other options, “in,” “to,” and “with,” do not combine with “count” to give the intended sense.So the completed sentence is “I have always counted on his friendship.”Answer:D. on