Feldspar and quartz are the correct answers
There are different reasons for formation off things. The blackheads are formed when sebaceous glands become clogged.
<h3> How do whitehead and blackhead form?</h3>
When sebaceous gland's duct is known to be blocked by sebum, a whitehead is therefore seen or show forth on the skin surface.
When the built up material oxidizes and dries, it therefore darkens, and then create a blackhead.
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The right answer is Mammalia is more specific than Animalia.
Mammals (Mammalia) are a taxon and a clade of vertebrate animals, which are themselves an Animalia taxon.
There are major general characteristics that make it possible to classify Animalia in branch lines.
* Arthropoda
* Mollusca
* Nematoda
* Chordata (Mammalia among others)
* Platyhelminthes
* Annelida
* Cnidaria
* Echinodermata
* Porifera ...