Magnesium is mainly present in the form of

Water-logged condition will quickly occur in which type of soil?

What percentage of the total phosphorus in vertebrates is incorporated into bones and teeth (in $\%$)?

Rhizosphere is the region where

Which element is responsible for causing soil salinity? At what concentration does the soil become saline?

Factors which determine to a large extent the vegetation of any area are:
$I.$ $pH$ of soil
$II.$ Mineral composition of the soil
$III.$ Water holding capacity of soil
$IV.$ Weather condition
Choose the correct option.