Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: What is the name of the course with the most registered students? | addresses : address_id , line_1 , line_2 , city , zip_postcode , state_province_county , country | people : person_id , first_name , middle_name , last_name , cell_mobile_number , email_address , login_name , password | students : student_id , student_details | courses : course_id , course_name , course_description , other_details | people_addresses : person_address_id , person_id , address_id , date_from , date_to | student_course_registrations : student_id , course_id , registration_date | student_course_attendance : student_id , course_id , date_of_attendance | candidates : candidate_id , candidate_details | candidate_assessments : candidate_id , qualification , assessment_date , asessment_outcome_code | students.student_id = people.person_id | people_addresses.address_id = addresses.address_id | people_addresses.person_id = people.person_id | student_course_registrations.course_id = courses.course_id | student_course_registrations.student_id = students.student_id | student_course_attendance.student_id = student_course_registrations.student_id | student_course_attendance.course_id = student_course_registrations.course_id | candidates.candidate_id = people.person_id | candidate_assessments.candidate_id = candidates.candidate_id | 

### Response:

select _ from _ group by _ order by count ( _ ) desc limit _ | select courses.course_name from courses join student_course_registrations on courses.course_id = student_course_registrations.course_id group by courses.course_id order by count ( * ) desc limit 1