How do I create a foreign key in SQL Server?

I have never “hand-coded” object creation code for SQL Server and foreign key decleration is seemingly different between SQL Server and Postgres. Here is my sql so far:

drop table exams;
drop table question_bank;
drop table anwser_bank;

create table exams
(
    exam_id uniqueidentifier primary key,
    exam_name varchar(50),
);
create table question_bank
(
    question_id uniqueidentifier primary key,
    question_exam_id uniqueidentifier not null,
    question_text varchar(1024) not null,
    question_point_value decimal,
    constraint question_exam_id foreign key references exams(exam_id)
);
create table anwser_bank
(
    anwser_id           uniqueidentifier primary key,
    anwser_question_id  uniqueidentifier,
    anwser_text         varchar(1024),
    anwser_is_correct   bit
);

When I run the query I get this error:

Msg 8139, Level 16, State 0, Line 9
Number of referencing columns in
foreign key differs from number of
referenced columns, table
‘question_bank’.

Can you spot the error?