Solar ponds are bodies of water in which circulation is

[RonPurewal]

...

do you have a question?
if so, please clarify. thanks.

[ZHENYUM85]

somewhat confused....

the crux of the argument is that this method = (the water in the solar pond was first made more saline through evaporation and then diluted by a rapid inflow of fresh water) "allows for effective control of nuisance algae", correct?

pls correct me if i am wrong, but it seems like both (C) and (D) provide alternative methods for the death of the algae. the reason why C>D is that D focuses on the algae that sank to the bottom of the pond. For that to happen, the method described in the passage (inflow causes algae to sink) has had to have worked, right? Thus, it seems somewhat incomplete and not nearly as strong of a counter-argument as (C).

If that is not the reason why C>D, can someone please explain.

thanks

(d) provides an alternative explanation, but it's still a result of the method described. i.e., the intermediate steps of the process are debated, but it's still clear that the original method is ultimately responsible for killing the algae. therefore, (d) doesn't undermine the conclusions at all.

I'm sorry but I disagree with your opinion. As you said, (d) is still a result of the method described, it's still clear that the original method is ultimately responsible for killing the algae . Isn't (c) the same? Part of the method is diluting the pond with a rapid inflow of fresh water , without it, how could there be "microorganisms'' in (c)? (c) is also a result of the method described.
I think maybe the difference between c and d is not regarding the process of the method, but about the consequence. maybe we should focus on the "cleanest technologies providing energy for human use" part? that microorganisms would make the result not so clean?

[RonPurewal]

Isn't (c) the same? Part of the method is diluting the pond with a rapid inflow of fresh water , without it, how could there be "microorganisms'' in (c)? (c) is also a result of the method described.

it's not the same.

the point at issue is that "the method ... allows for effective control of nuisance algae".

as described, "the method" just involves an influx of fresh water—i.e., random fresh water. "the method" does not control for whether the water contains bacteria that kill algae.

if (c) is true, then, if fresh water WITHOUT these bacteria is used, then "the method" will fail. so, the characterization of the method in general as "effective" is now in serious doubt.

by contrast, (d) doesn't depend on anything that is not already accounted for.