Answer:
Select
a and c
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Answer:
*dark, dense- igneous rocks(gabbro & basalt)
*light colored with mineral crystals- igneous rocks (Rhyolite)
*most common rocks on earth's surface-sedimentary rocks
*found under the oceans- igneous, sedimentary and metamorphic rocks (gabbro, basalt, serpentine, peridotite, olivine and ore minerals)
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Explanation:
Sediment discharge was historically approximately 270 million cubic meters/year of suspended load and 130 million cubic meters/year of bedload. This has decreased 80% since 1850 and can be divided into three periods: historical period (pre 1900), pre-dam period (1932-1952), and post dam (1963-1982). Suspended sediment loads declined 43% between the historical and pre-dam and 51% from pre-dam to post-dam periods. The size of sediment also decreased drastically including a 72% decrease in the sand fraction. Most of this is due to dams on the tributaries acting as sediment traps primarily for the coarser sediments. Large-scale land clearing for agriculture contributed to increased sediment loads in the historic period.
It is called THERAPEUTIC INDEX. Therapeutic index is the comparison of the amount of a particular drug that causes the desired therapeutic effects and the amount that causes toxicity. The index can be low or high. A drug with a low therapeutic index will require only a small increase in dose to produce toxic effects in users.