The answer is D,Nucleus I think
One problem with this hypothesis is that the student didn't write about why this hypothesis might work - what is the underlying mechanism. The thing is that one might want to write the underlying mechanism or explanation in his hypothesis. Another problem with this hypothesis is that it's very hard to measure and be sure that following exposure to white chocolate, people are happier and that it's not a consequence of something else.
Correct answer: A) Extension
Extension is a physical position that occurs when angle between the bones and the limbs of joint increases.
It takes place when there is a contraction of muscles and bones move the joint from a bent to a straight position, it is opposite of flexion, in which the angle between the bones and the limb at the joint decreases.
Example: During straightening of the leg, the angle between the tibia and femur increases, which shows extension has taken place.
Explanation:
purines-Double carbon-nitrogen ring with four nitrogen atoms
pyrimidines-Single carbon-nitrogen ring with two nitrogen atoms
Which processes..? There is not enough information for a solid answer to be given.