White blood cells are especially active when you are sick because their primary job is to fight off infections – often bacteria or viruses that do not belong in you. Once they locate the invader making you sick, they eat it and destroy it. What organelle do you think is plentiful in white blood cells?

Lysosomes

Explanation:

Lysosomes are membrane bound organelles that contain degradative enzymes. They degrade worn-out cellular parts and may also be used by cells to degrade/destroy invading bacteria or viruses. Hence, since white blood cells are primarily responsible for fighting infections, it is expected that they have a high amount of lysosomes (which they indeed do have in high amount).

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.