SELECT DISTINCT Applies to multiple column 'selections'?

select distinct q.user_id,
h.user_id is not null as ‘is_home_try_on’,
h.number_of_pairs,
p.user_id is not null as ‘is_purchase’
from quiz as ‘q’
left join home_try_on as ‘h’
on q.user_id = h.user_id
left join purchase as ‘p’
on q.user_id = p.user_id
limit 10;

In the above code, am I specifying to select the distinct user_id from each of the tables (alias q, h, and p)? Or to just select the distinct user_id from table alias as q?