How do enzymes affect reactions?
o
a. enzymes are used up in reactions.
o
b. enzymes cause reactions that normally release energy to absorb
energy
o
c. enzymes prevent reactions from occurring.
o
d. enzymes lower the activation energy required for reactions to
occur.

it,s D

Explanation:

Enzymes are known as biological catalyst and work by lowering the activation energy of a reaction. They do this by providing an alternative pathway which speeds up the reaction without the catalyst undergoing a permanent change. ... An important thing to remember is that enzymes do not affect the equilibrium of a reaction.

because of

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]