The major difference between a grand mal and a petit mal seizure is the presence or absence of:
a. an altered state of consciousness.
b. migraines and disorientation.
c. motoric abnormalities.
d. extreme emotional responsiveness.

c. motoric abnormalities.

Explanation:

The major difference between a grand mal and a petit mal seizure is the presence or absence of motoric abnormalities.

(C). Motoric Abnormalities. 

Explanation:

Grand mal seizure is a form of seizure involving a loss of consciousness, and violent contractions of the muscle, it causes a loss of consciousness and violent muscle contractions.

A petit mal seizure also known as absence seizure causes you to blank out or stare into space for a few seconds, it is caused by abnormal and intense electrical activity in the brain.

Motor abnormalities are nervous system disorders which cause abnormal and involuntary movement, Such disorders may result in lack of movement or an abundance of uncontrollable shaking.

There is a presence of MOTOR ABNORMALITIES, both in the Grand mal seizure and Petit mal seize also, the both involves unconsciousness and involuntary movements.