What is an indication that a lake is healthy? A. a pH of 3.5

B. a pH of 10.5

C. low number of bioindicators

D. high number of bioindicators

D

Explanation:

As bioindicators are the organism that indicate or monitor the health of the environment

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.