How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
a. by binding at the active site of the enzyme
b. by changing the shape of the enzyme's active site
c. by changing the free energy change of the reaction
d. by acting as a coenzyme for the reaction
e. by decreasing the activation energy of the reaction

Answer :B. By changing the shape of the enzyme's active site.

check the attachment

Explanation: This is a type of inhibition , in which a molecule binds to another part of the enzyme instead of the  active site.

On binding, it disrupts the  normal hydrogen bond and hydrophobic   interactions holding the enzyme molecule in its three dimensional shape, therefore distorting the conformation and   ACTIVE SITE of the  enzyme (changed it shape).

Since the active site is the precise location enzyme must bind with substrates for enzymatic reactions,this makes the enzyme not fit  for binding with the substrate, therefore  the efficiency  is reduced. No substrate-enzyme complex, and hence no substrate-product  complex for the release of  products, this brings down the turnover rate and eventually

the rate of reaction of the enzyme

Thus, the enzyme function is totally blocked, even in high concentration of the substrate,