Question: Isabella Kelly was born in a castle that is at the northern extremity of which isles?

Context paragraphs:
Cape Poinsett: Cape Poinsett ( ) is an ice-covered cape in Antarctica, the northern extremity of Budd Coast, from which the coast recedes abruptly to the southeast and southwest.  The position of Cape Poinsett correlates closely with the high seaward extremity of "Budd's High Land" as charted in 1840 by the United States Exploring Expedition under Lt. Charles Wilkes.  The cape was plotted from air photos taken by USN Operation Highjump, 1946–48, and named by the Advisory Committee on Antarctic Names (US-ACAN) after Joel R. Poinsett, Secretary of War under President Martin Van Buren, who was instrumental in the compilation and publication of the large number of scientific reports based on the work of the United States Exploring Expedition.

Tea Gardens, New South Wales: Tea Gardens is a locality in the Mid-Coast Council local government area, located near the southern extremity of the Mid North Coast and the northern extremity of the Hunter Region in New South Wales, Australia.

Cairnburgh Castle: Cairnburgh Castle is a ruined castle that is located on the islands of Cairn na Burgh Mòr and Cairn na Burgh Beag, Argyll and Bute, Scotland.  These islands are at the northern extremity of the Treshnish Isles at the mouth of Loch Tuath, Mull north of Iona.  1991's "The Changing Scottish Landscape" characterizes it as "one of the most isolated fortifications in Britain...[and] also one of the strangest."

Slade Point (South Australia): Slade Point is a headland located on the west coast of Eyre Peninsula in South Australia about 29 km south of the town of Streaky Bay.  The point is the northern extremity of Searcy Bay and the southern extremity of a promontory that separates Searcy Bay in the south east from Sceale Bay in the north west.  While it is within the coastline first charted by Matthew Flinders on 9 February 1802, it is not named by Flinders possibly due to the coastline being obscured by a thick haze.  Slade Point was named in 1908 after “the late Mr. W. E. Slade” who served as the Assistant Engineer of Harbours in the South Australian Government.  The cape has adjoined the boundary of the Cape Blanche Conservation Park since 2012 while the waters adjoining its shoreline have been within a habitat protection zone in the West Coast Bays Marine Park also since 2012.

Saskatchewan Highway 19: Highway 19 is a highway in the Canadian province of Saskatchewan connecting Highway 15 northern extremity near Hawarden to Highway 18 at the southern extremity near Mankota.

Nordwestliche Insel Mountains: Nordwestliche Insel Mountains ( ) is a small, detached group of mountains, island-like in appearance, and forming the northern extremity of the Humboldt Mountains, in the Wohlthat Mountains of Queen Maud Land.  Discovered by the German Antarctic Expedition under Ritscher, 1938–39, and named Nordwestliche Insel (northwest island).  The feature lies at the northwest extremity of the Wohlthat Mountains.

Acre, Israel: Acre ( or , Hebrew: עַכּוֹ‎ , "ʻAko", most commonly spelled as Akko; Arabic: عكّا‎ ‎ , "ʻAkkā") is a city in the northern coastal plain region of the Northern District, Israel at the northern extremity of Haifa Bay.  The city occupies an important location, as it sits on the coast of the Mediterranean Sea, traditionally linking the waterways and commercial activity with the Levant.  The important land routes meeting here are the north–south one following the coast and the road cutting inland through the Plain of Esdraelon; Acre also benefits from one of the very rare natural harbours on the coast of the Land of Israel.  This location helped it become one of the oldest cities in the world, continuously inhabited since the Middle Bronze Age some 4000 years ago.

Cape Blanche: Cape Blanche is a headland located on the west coast of Eyre Peninsula in South Australia about 25 km south south-west of the town of Streaky Bay and about 4 km west of the town of Sceale Bay.  The point is the southern extremity of Sceale Bay and the northern extremity of a promontory that separates Sceale Bay in the north west from Searcy Bay in the south east.  While it is within the coastline first charted by Matthew Flinders on 9 February 1802, it is not named by Flinders possibly due to the coastline being obscured by a thick haze.  The cape is reported as being one of the sixteen features named in South Australia after Blanche Ann Skurray, the wife of Richard Graves MacDonnell, the sixth Governor of South Australia who served from 1855 to 1862.  The cape has been within the boundary of the Cape Blanche Conservation Park since 2012 while the waters adjoining its shoreline have been within a sanctuary zone in the West Coast Bays Marine Park also since 2012.

Cape Freels: Cape Freels is a headland on the island of Newfoundland, in the province of Newfoundland and Labrador, Canada, and the location of a community of the same name.  This cape, located at the northern extremity of Bonavista Bay, is not to be confused with another Cape Freels which is located at the southern extremity of the Avalon Peninsula of Newfoundland.

Isabella Kelly: Isabella Kelly, née Fordyce, also Isabella Hedgeland (born at Cairnburgh Castle in the Scottish Highlands and baptised on 4 May 1759 – died on 25 June 1857 in London) was a Scottish novelist and poet.

Supporting paragraphs: Isabella Kelly Cairnburgh Castle
Answer: Treshnish Isles