Final answer:
In 'A Wrinkle in Time,' the Black Thing has the power to spread darkness and evil, enforcing conformity and suppressing individuality through mind control.
Step-by-step explanation:
In A Wrinkle in Time, the power that Meg must battle against is c) The power to spread darkness and evil. This ominous force, known as the Black Thing, represents a form of universal darkness and is essentially the manifestation of evil. It seeks to consume planets and civilizations, enforcing conformity and extinguishing individual thought and creativity. The Black Thing's influence is primarily through mind control, making entire populations submit to a single, unified way of thinking devoid of any dissent or deviation. It is not directly associated with manipulating time or seeing the future, but rather with an all-encompassing darkness that seeks to obliterate freedom and goodness.