Charlene uses “relies” to mean “uses”: cleanup efforts are using microorganisms more and more. Olaf’s reply is consistent with that, though. “Relies” is a term with stable enough meaning that it’s hard to generate a good example of equivocation. Maybe Olaf suggests cleanup efforts literally lean on microorganisms or something.

The rightness of (B) should shed light on the wrongness of the other answers. Charlene uses normal to mean normal for the region. Like “it’s usually instant-death hot here in the Sahara, but the temperature is lower than normal, so it’s only torturously hot today.”

Olaf counters with evidence comparing microbes from two regions with different temperatures (Arctic temps are lower than subtropical temps). This doesn’t address Charlene’s argument about temperature drops within a given region.

But Olaf was trying to make sense, and the best way to explain his reasoning is that he was trying to undermine the idea that microorganisms are less effective when a region’s temperature drops below what’s normal on the planet earth. “Arctic temperatures aren’t normal, and these microorganisms are doing just fine!”

Charlene uses cleanup to mean “getting rid of” pollutants, like how you clean up trash. Olaf’s evidence is consistent with that – his talk of microbes eating oil refers to the same goal of cleaning up / getting rid of pollutants.

Equivocating on “cleanup” would be Olaf saying “microbes are perfectly capable of making our environment nice and tidy and orderly!”

Charlene uses limitations to mean “downsides”, or to suggest microorganisms aren’t a complete solution to all our pollutant problems.

Olaf’s rebuttal addresses that contention cleanly – he’s arguing that microorganisms are not subject to the limitation Charlene presents.

There’s certainly a difference in terminology between Charlene’s argument, which talks about microbes being active, and Olaf’s argument, which talks about microbes eating oil. And plenty of LSAT questions demand that you notice that difference – “Olaf assumes eating oil is the same as activity!”

But this question isn’t about whether these concepts are the same – it’s about whether these two authors treat them the same. Charlene uses “active” to mean “metabolizing pollutants”, and Olaf’s evidence also measures the rate at which microbes metabolize pollutants.