The assumptions made in calculating the michaelis-menten equation include
a) that the value of k-2 can be ignored.
b) that the concentration of the substrate is greater than the concentration of e.
c) that the formation and decomposition of es is the same for a period of time.
d) a, b and c.
e) a and b only.

c) that the formation and decomposition of ES is the same for a period of time

Explanation:

Michaelis-Menten equation :

This model  explain the approach to enzyme kinetics.The Equation shows how a Free enzyme E and Product P is formed depicting by Following equation.

                       E+S⇌ES→E+P

Left side represents

E =enzyme

S=substrate

ES=enzyme-substrate complex

Right side

E= Free enzyme

P= product

c) that the formation and decomposition of ES is the same for a period of time

i believe the answer is a.