Not getting fieldset as a option while adding new fields in content type
There's no 'fieldset' field type as such.

If you want to wrap entity fields in fieldsets, install the Field Group module:


  Fieldgroup will, as the name implies, group fields together. All fieldable entities will have the possibility to add groups to wrap their fields together. Fieldgroup comes with default HTML wrappers like vertical tabs, horizontal tabs, accordions, fieldsets or div wrappers.