Correct option is C
Explanation-
Option C - "Most likely there is a cause-effect relationship between the two traits."
This is correct under the assumption that:
The ecologist has done more than just observe correlation — possibly through controlled experiments or statistical controls that suggest one trait influences the other.
For example, it's biologically reasonable to assume that as shell thickness increases, weight also increases, since both are physical properties of the shell structure. This is plausible biologically and the phrase "most likely" implies a strong correlation that may suggest causation, without stating it as a fact.
Thus, in this context, the statement is cautiously worded and suggests a probable causal link, not a confirmed one — which makes it acceptable.
Incorrect options -
Option A - “Heavier molluscs are better defended from predators”
No predator data or observations are mentioned in the study.
Cannot be concluded from correlation alone.
Option B -“Heavier molluscs are poorly defended from predators”
Same issue as above — no evidence of predator interaction is provided.
Option D - “Weight and thickness are variable traits”
While this is true, it is a weaker conclusion than Option 3.
It doesn’t capture the significance of the observed correlation.
