A solution with a high concentration of H ions A) shows a pH of 7
B) kills all organisms
C) has a high pH
D) is very acidic

A solution with a high concentration of hydrogen ions (
H
+
)
is an acid or an acidic solution. The higher the concentration of hydrogen ions (measured in mol/l or moles per litre) the stronger the acidity of the solution. This is usually measured in pH values calculating pH as
−
log
[
H
+
]
. Any value below 7 (corresponding to
10
−
7
m
o
l
/
l
) is acidic.

(Sorry I tried to write it the best I think this is the answer, if so hope it helps!)