Activation energy:.a) is the energy needed by an enzyme to catalyze a reaction without coenzymes. b) given off as the products in a chemical reaction are formed. c) required for a chemical reaction to begin. d) absorbed as ΔG0 moves from negative to positive.

c) required for a chemical reaction to begin.

Explanation:

Activation energy is the minimum amount of energy required to initiate a chemical/bio-chemical reaction. Most of the reactions are slow because they require a lot of energy to get initiated. So in order to initiate reaction, enzymes provide an alternate pathway which requires comparatively less amount of energy. Substrate of a reaction binds to the enzyme which results in change of shape of the substrate in such a manner that ultimately causes activation energy to get lowered. In short we can say that enzyme holds the substrate in such a manner that requires less activation energy and hence increases the catalysis.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

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)]