What conditions in Alaska make petroleum oil formation possible in the area. (Northern part?)?

Question

Because.............
A.Alaska has always been cold?
B.Alaska was once warmer, shallow sea with lots of life?
C.Alaska is a special place where heat was not needed to produce petroleum?
D. Alaska has lots of shale, which stores lots of oil?

Answer 1

B.

World climates have changed incredibly over the last 300 million years and the continents have moved around. There are temperate and semi-tropical fossils, including dinosuars found in Alaska.

Answer 2

B
D is almost right but shale is a source rock not a reservoir.