The is (are) responsible for the red blood cell's ability to transport oxygen.
a. hemoglobin
b. leukocytes
c. platelets
d. hematocrit

(A). hemoglobin

Explanation:

Hemoglobin is iron-containing protein, present in RBCs (red blood cells) of nearly all vertebrates and some invertebrates.  It is made up of four globular protein units.

The main function of hemoglobin is to transport oxygen to the different parts of the body. The oxygen is requires by the body cells to perform cellular respiration that generates energy in the form of ATP molecules.

Thus, the correct answer is option A.

spiders belong to a group of arachnids.

arachnids have the following traits :

they have two body parts.

they have eight legs unlike insects which have 6 legs.

they have no wings.

these traits distinguish them from insects.

the information that antonio is doubting us the statement that spiders differences are as a result of being first to evolve.

this is because the evolution of one species is independent of the other species.

the real answer is b. scintillation counter