Hii,i will help you according to your query.Yes it is included in your best four subject.Well take an example i too have passed my 12th this year by CBSE board and i have got the following marks

economics 98

business studies 97

physical education 91

accountancy 90

english 83

maths 68

if i calculate my best 4 % including physical education then i secure 92.25%

which is equals to 89.75% as per prospective of DU

and if i calculate without it it will be 92%

so its better not to include phyical education marks in best 4 if you are getting a score equal to your real best 4

Hope,this information will helpful for you.Goodluck.