A table question with a claim that has two parts tests whether you can support the whole claim with numbers. Read the claim first, and split it into parts to work out what the data must show. Then read the title and column headings to learn what the numbers measure and which groups they describe. Work out which numbers each part needs, and check every difference a choice reports. Accurate numbers can still leave part of the claim unsupported.
Hints
- Hint 1
Look at the two parts of the researchers' claim. What does it say about later salinity shifts, and what does it say about predictable salinity?
- Hint 2
Match each part of the claim to the table's test conditions. Which columns describe salinity shifts, and which describes salinity that stays predictable?
- Hint 3
Decide which rates each part of the claim needs. What would those comparisons tell you about the claim?
Step-by-step
Compare histories under each test condition
Step 1Split the claim into two parts
The claim pairs broad resilience to later salinity shifts with a cost when salinity remained predictable. What would support both parts? We need fluctuating-history populations to grow faster after both an increase and a decrease, but more slowly under unchanged salinity. Both the benefit and the cost need evidence.
- Step 2
Read matching test conditions
The table's rows show salinity history, while its columns show the test condition. The measure is mean growth rate in cell divisions per day, so higher numbers mean faster growth. Which rates should we compare? Read down each column to compare constant-history and fluctuating-history populations under the same test.
- Step 3
Check what each comparison leaves out
Do the choices cover all three conditions? Relative to their own unchanged-salinity rates shows drops within each history, but doesn't show the cost under unchanged salinity. The choice with grew division per day more slowly covers the cost and the increase, but compares the rate after a decrease only with the fluctuating history's own unchanged rate. The two shifted-condition rates differed compares the shifts within each history. These comparisons leave part of the claim untested.
- Step 4
Calculate the full comparison
Subtracting constant-history growth from fluctuating-history growth gives 2.4 − 2.8 = −0.4 unchanged, 2.2 − 1.5 = 0.7 after an increase, and 2.1 − 1.7 = 0.4 after a decrease. The negative gap shows the cost, and both positive gaps show a growth benefit after shifts. The choice giving these three differences supports the whole claim. Choice C.