"working on" and "racing to develop" meant the same thing to me, whereas "investing all their resources on developing" is something that is randomly introduced. The paragraph doesn't indicate that the company is using everything they have to develop a vaccine.

@shay_lsat sometimes, if an answer choice introduces new words ("investing all resources"), i automatically cross out the answer choice because those words (or even similar words) were NOT used in the original prompt.

Plant life cannot survive without atmospheric carbon.

1. Find the Conditional Indicator

   "Without" (group 3)

2. Identify the main concepts(groups, categories, events, or ideas)

   Idea 1: "cannot survive"

   Idea 2: "atmospheric carbon"

3. Assign symbols

   cannot survive (/S)

   atmospheric carbon (AC)

4. Apply Lawgic:

"atmospheric carbon" comes after "without", so we negate that idea and make it the sufficient...

AC becomes /AC

Next, you make the other idea ("cannot survive") the necessary condition:

/AC-->/S

the contrapositive would be:

S-->AC

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Your mistake was thinking the conditional indicator, "without", was attached to "atmospheric carbon"

which makes you translate "without atmospheric carbon" into /AC

so when you used Group 3 Lawgic, your process turned /AC into AC

which is why you got

/S--AC or /AC--S

does this make sense?