Can you please help me with this
A) He is the only one of the students who has already taken latin
B) He is the only one of the students who
have already taken latin
I would go for B since 'who' I think means students - reason immediate proximity - refferent rule.
Also is the meaning he is the only one (with dyed hair) among those who have taken latin - as in B?
or he is the only one who has taken latin among the students - as in A
Meaning is more clear in A - but refferent rule points to B
I agree with b14kumar that we have to count on the meaning of the sentence, to see to whom/which the "who" clause really refers to/ modifies.
In the first sentence, we are talking about the unique characteristic of "he" ..how it is, only "who" clause makes it clear that he "has taken Latin" ---> who clause directly modifies the subject " he" ---> the verb should be "has"
In the second one, we're talking about a "he" belonging to a group. How that group is? ..."who" clause makes it clear: a group of those who have taken Latin --> "who" clause modifies "students" ---> verb should be "have".
The sentence in this case falls into the first type --> A is better.