It occurs because of contraction of the muscle layers. There are two types of muscle found in the alimentary canal; longitudinal and circular muscle, the alternating contraction of these muscles forces the bolus of food through the digestive system.
I feel it is the contribution on cotemporary physics.
This is more current than even modern physics.
Please mark me as brainliest.
1. bees and flowers - <span>coevolution
</span><span>2. cichlid fishes- </span><span>divergent evolution
</span><span>3.flying squirrel and flying phalanger - </span><span>Pairs convergent evolution</span>
A phylogenetic tree is a branching diagram showing evolutionary relationships among various living organisms based upon similarities and differences in their physical or genetic characteristics like the one above. In this case a human is more closely related to a mouse than a kangaroo, A platypus is more closely related to a kangaroo than a mouse, a human and a kangaroo share common features because of a common ancestor.
The best and most correct answer among the choices provided by the question is the fourth choice. The procedure that could be done to increase the validity is to m<span>easure the oxygen in liters. </span>I hope my answer has come to your help. God bless and have a nice day ahead!