Cynthia’s psychology professor asks the class not to think about purple unicorns. Though Cynthia has never once before thought abouta purple unicorn, she finds that she cannot stop thinking about them. Cynthia is experiencing as a result of her attempts at .
a. the rebound effect; ruminationthe
b. rebound effect; thought suppression
c. distraction; rumination
d. distraction; thought suppression

Cynthia is experiencing b. rebound effect as a result of her attempts at thought suppression.

Explanation:

Thought suppression is the conscious, motivated way of trying to erase or remove a certain thought. This conscious activity often leads to the rebound effect, which creates the opposite outcome; the individual will most likely keep thinking about this specific thought.

In this case, Cynthia's conscious act of trying not to think about a purple unicorn, leads to the rebound effect, in which she cannot stop thinking about it.

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.