The familiar slogan “survival of the fittest” is popularly used to exp

The argument basically says this -

the slogan "survival of the fittest" --> Neither informative nor of scientific interest.

A - Incorrect.

the option says "all claims that are of scientific interest are informative" - this connects the two parts of the conclusion.
It does not link the premise to the conclusion. i.e. does not tell us why/how that particular slogan is neither informative nor of scientific interest.

B - Incorrect.

We know that this is not correct because the argument claims that the slogan is true but of no scientific interest.

C - Incorrect.
Negate this -
"Popular slogans are often informative and of scientific value" - does not mean that they are always informative or of scientific value.
Hence, we are not sure how applicable this is to the slogan mentioned. Hence, incorrect.

D - Incorrect.
negate this -
"Informative scientific claims can use terms in the way they are popularly used"
does not mean that the slogan mentioned is not informative and has no scientific value.

E - Correct
If this option is negated, then the argument falls apart -
"The truth of a purported scientific claim is sufficient for it to be of scientific interest" --> we know that the slogan mentioned is true --> hence, it is of scientific interest.