To classify an unknown substance as a metal or a nonmetal, a group of students prepared the table shown. The table compares the properties of four known substances to the properties of the unknown substance.
Substance Substance Type State at Room Temperature Reaction with Water Reaction with Oxygen Electric Conductor
Sodium
Metal
Solid
Violent release of gas
Yes
White solid
Zinc
Metal
Solid
None
White solid
Yes
Nitrogen Nonmetal
Gas
None
Reddish-brown gas
No
Sulphur Nonmetal
Solid
None
Colorless gas
No
Unknown
Unknown
Solid
None
Yes
Brown solid
On the basis of the table, the students concluded that the unknown substance is most likely a metal.
What is most likely the reasoning the students used to classify the unknown substance as a metal?
A. The unknown substance reacts with oxygen.
OB. The unknown substance conducts electricity.
O C. The unknown substance does not react with water.
O D. The unknown substance is a solid at room temperature.

The answer is texture

Mantle convection  is the slow  creepingmotion of earth's solid silicate  mantle  caused by  convection  currents carrying  heat from the interior  to the planet's surface.[1][2]  the earth's surface  lithosphere, which rides atop the  asthenosphere  (the two components of the  upper mantle), is divided into a number of  plates  that are continuously being created and consumed at their opposite  plate boundaries. accretion occurs as mantle is added to the growing edges of a plate, associated with  seafloor spreading. this hot added material cools down by  conduction  and  convection  of heat. at the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of  subduction  usually at an  ocean trench.[3]this subducted material sinks through the earth's interior. some subducted material appears to reach the lower mantle,[4]  while in other regions, this material is impeded from sinking further, possibly due to a phase transition from  spinel  to  silicate perovskiteand  magnesiowustite, an  endothermic reaction.[5]the subducted oceanic crust triggers  volcanism, although the basic mechanisms are varied. volcanism may occur due to processes that add buoyancy to partially melted mantle causing an upward flow due to a decrease in density of the partial melt.secondary forms of convection that may result in surface volcanism are postulated to occur as a consequence of intraplate extension[6]  and  mantle plumes.[7]it is because the mantle can convect that the  tectonic plates  are able to move around the earth's surface.[8]mantle convection seems to have been much more active during the  hadean  period, resulting in gravitational sorting of heavier molten  iron, and  nickel  elements and  sulphides  in the core, and lighter  silicate minerals  in the  mantle.