Sedimentary rock is the most likely. Igneous and metamorphic rocks go through too much pressure and heat for fossils to be preserved. The bones would just melt away.
True, the trachea is a cartilaginous tune that connects to the pharynx and larynx.
Nails are made of iron because, iron is strong and sturdy; although nail rust when it undergoes oxidation when expose to water but it is not explosive.
Barium and phosphorus are not suitable for nail making because of their properties.
Barium is an element which reacts with virtually all non metals, forming poisonous products which are dangerous to health and to the environment. It also reacts explosively with water.
Phosphorus is not found in its pure form in nature, it conducts electricity and it is combustible in nature.<span />
The answer to this question about the evolution of the gymnosperm plants would be C. They evolved after the seedless vascular plants.
Gymnosperms, or sometimes termed as seed plants, are classified as vascular plants and has been thriving for centuries on earth through producing seeds. They are multicotyledonous and are the opposite of flowering plants. Conifers would be the most abundant group of gymnosperms while the cycads come in second. Gingko would place last with just having one species under its name.
