The correct options are
A Bangladesh has a high density of population.
B Areas of high population density have above 50 people per sq.km.
Areas of high density (above 50 people per sq.km.) include East Asia, South Asia, North-West Europe & Eastern North America.
Areas of moderate density (10 to 50 people per sq.km.) include subtropical regions like Angola, Congo, Nigeria and Zambia in Africa.
Areas of low density (less than 10 people per sq.km.) include Central Africa, Western Australia, Northern Russia, Canada, etc.