Which of the following elements is a key component of adenosine
triphosphate (ATP?)

Nitrogenous base and phosphate.

Explanation:

Nitrogenous base and phosphate group are the elements which is considered as the key component of adenosine  triphosphate (ATP).  adenosine  triphosphate comprise of nitrogenous base, the sugar, ribose, adenine and three phosphate groups attached to ribose.  This adenine triphosphate is used by the cell for the production of energy needed for different cellular activities.

answer; ///(b) it is composed of four protein chains and four heme groups;

hey bro i looked it up on google the structure of the eye-spot in euglena viridie, e. ehrenbergii, and phacus pyriyorme is not as franzé haa described it. the so-called “crystal body” and “lens bodies” were not found in any of the individuals of the species examined by me. as earlier observers have stated, the eye-spot consists simply of a mass of pigment granules arranged in a single layer, and probably embedded in a protoplasmic framework, but the latter could not be seen, and its presence was only inferred from the fact that the pigment granules must be held together in some way, thd the eye-spot as a whole is capable of expansion, and that the pigment granules can be separated from each other.

hope this   and an i get brainlsiest