Since the air is a great thermal isolator, the windows prevent heat exchange better than one made out of a single thick sheet of glass. The air between the thin blankets is not moving around and will form an isolating layer that acts exactly like another blanket, thus improving the thermal isolation
Alleles that are masked by others are called recessive alleles.
Answer: The 3rd one, answer C
Infectious agents are those that corrupt and prey on an organism or a host. This is sometimes called parasitism when a foreign organism consumes a host by preying on its nutrients and food. Hence, we are uncertain in Anna's case because there is no clear description of her symptoms.