A. <span>Exposure to an antigen
Exposure to viruses and antigens led to the foundation of modern vaccination. Vaccination introduces an antigenic material that helps the ability of the immune system to adapt a specific pathogen, therefore leading to a long-term immunity.</span>
The second law of thermodynamics states that not all of the energy is used because some of the energy is lost in the form of heat. The lost heat energy is an unusable form of energy, and it causes an increase in the entropy of the universe. Thus, no energy transfer process is efficient due to the loss of energy.
The outer planets are mostly formed of lighter elements because these three condense are a<u> lower temperature</u>.
<u>Explanation:</u>
The planets based on the location of the sun is divided into two, that is outer planets and inner planets.
The Outer planet which is far from the sun consists of larger quantity of lighter substances such helium, hydrogen, methane which would condense at the lower temperature. And remains gaseous inside the frost line that would exit far away for the sun so the temperature is low and the lighter materials are easier to condense in lower temperature to form terrestrial rocks.
<span>the definition: Behavioral adaptations are the things organisms do to survive. For example, bird calls and migration are behavioral adaptations. Adaptations are the result of evolution. Evolution is a change in a species over long periods of time. The Answer is D. Protective over young cubs</span>
