<span>The menstrual cycle is the set of physiological phenomena, occurring most often periodically (approximately one month), which prepare the body of the woman for a possible fertilization.
The process signal of the end of one cycle and the beginning of a new one is menstruation which is explained by the release of the unfertilized ovule with the placenta precursor (which is a blood).
In the case of fertilization, the menstrual cycles are "paused", and "resumed" after the childbirth.</span>
Metamorphic rocks are formed from existing rocks, when it is exposed to great heat and pressure. This process would destroy any fossils inside the already existing rock.
<span>The carapace or shell is an exoskeleton or external skeleton found in certain invertebrates. The carapace provides protection and rigidity to the organism. In rats the skeleton gives rigidity and protects organs.
Also, the muscular system helps in maintaining shape and helps protect many organs.
Hence the skeleton and muscles in rats perform equivalent functions as the carapace of other animals.</span>
The answer is A. <span>They can interbreed and produce fertile offspring.</span>
The heart is a prime exaple because similar to the plasma membrane the heart pumps oxygenated blood through out the body, circulatory system