What is implied by the web of causation model?
a. variables interact resulting in higher probability of illness.
b. one disease causes another, especially in vulnerable populations.
c. the greater the poverty, the more likely people are to have diseases.
d. immunizations are necessary because vulnerable populations spread disease.

a. Variables interact resulting in higher probability of illness.

Explanation:

Causality is the relationship between an event A (the cause) and a second event B (the effect), provided that the second event is a consequence of the first. Causality is logically identified in "if not A, then not B", provided the empirical occurrence of at least one B. The above expression is not strictly equivalent to the expression "if A then B", but this is not that the one usually linked in common sense to the concept of causality. Many causal models are used to explain phenomena, whether in science or common sense. In biological sciences, the use of chance models asserts that variables interact resulting in a higher probability of a disease.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave