How do plants influence the uptake of cations such as magnesium involving cation exchange?

The soil cations are essential for plant growth. It is enabled by cation exchange.

Dihydrogen monoxide or simply water in soil reacts with carbon dioxide and produce carbonic acid. The carbonic acid releases protons. This cation exchange is compelled by the release of carbon dioxide by root cells.

i believe you meant to say air rather than hair so the answer is below ")

the dead sea, the lowest place on earth at 430 metres (1,410 ft) below sea level, has a correspondingly high typical atmospheric pressure of 1065 hpa.

the answer to your question is:

c. complementary base-pairing