What attribute of a comet would be sufficient to conclude that it is from the Oort cloud?

a. If its orbit is near the plane of the ecliptic.  

b. If its orbit is highly inclined to the ecliptic.

c. If its orbital period is very long (such as 10,000 years or more).

d. If it has a highly eccentric orbit (highly elongated ellipse or parabola).

e. If it has never been seen before.