condtion based xml for each row of the table t-sql

Hello ,

i have below data.

create table #students
(
        id int identity(1,1) primary key,
        student_id int not null, 
        [s_m_cml] xml
)

 insert into #students
 (
        student_id,
        [s_m_xml]
 )
 values
 (
        101,
        '<submarks><submark><subject>Arts</subject><marks>85</marks></submark><submark><subject>Science</subject><marks>95</marks></submark><submark><subject>maths</subject><marks>100</marks></submark></submarks>'

 ),(102,'<submarks><submark><subject>Arts</subject><marks>50</marks></submark><submark><subject>Science</subject><marks>75</marks></submark><submark><subject>maths</subject><marks>85</marks></submark></submarks>')
 
 select * from #students

if all subjects- marks in s_m_xml marks > 80 then i select the row as promoted else as demoted. the exact output should look like below.

 
 student_id     [status]
 ---------------------------
 101             promoted
 102             demoted

what is the best way to achieve this using t-sql. Thanks in advance for any suggestions.