What happens as the activation energy increases?
a. the pressure of the system decreases.
b. the kinetic energy of colliding molecules changes.
c. the reactant surface area decreases.
d. the reaction begins to slow down.

kinetic energy of the colliding molecules changes.

Explanation:

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.