Sentence correction "This species" vs. "these species"

[bernardofrancomillan]

Hello -

This is related to a CAT question I ran into a few days ago (SC):

"Found even in ancient Egyptian mummies, the parasitic Guinea worm became the focus of a global public health campaign in 1986; this species of parasite has declined for two decades, and may finally be eradicated from the earth by 2010"

A. Same
B. Being the focus of a global public health campaign since 1986 and found even in ancient Egyptian mummies; the population of the parasitic Guinea worm has
C. Having been the focus of a global public health campaign in 1986, it was found even in ancient Egyptian mummies; the frequency of the parasitic Guinea worm
D. Being found even in ancient Egyptian mummies and having been the focus of a global public health campaign since 1986, the frequency of the parasitic Guinea worm
E. Having been found even in ancient Egyptian mummies and being the focus of a global public health campaign since 1986, the parasitic Guinea worm species

I agree that B-E are wrong but I was thrown out by "this species of parasite" on answer "A". I would have written "this specie of parasite" or "These species of parasites".

Thoughts?
Thx,
Bernardo

[Ben Ku]

The word "species" is either singular or plural depending on its usage. The singular form is NOT specie.

This species of rabbits has darker fur than all the other species of rabbits.

[RAHULS852]

Hi Sage / Manhattan Expert,

In (E) apart from all mentioned errors, is removal of "has" right ?

1) this species of parasite has declined for two decades
2) the parasitic Guinea worm species declined for two decades.

I think use of "has" is necessary to define the action that continued for 2 decades.
If sentence had mentioned "in 2018" then use of declined would have right.

the parasitic Guinea worm species declined in 2018.

Kindly review my understanding.

Regards,
Rahul Singh

[Sage Pearce-Higgins]

I agree with you that the sentence needs the verb 'has declined' to be logical. However, the mention of 'two decades' isn't important here. The crucial issue is that the use of the present perfect ('has declined') here suggests that the action is still going on in the present. The mention of eradicating the parasite makes this the logical meaning.

In a different context, we could use 'declined' if the action has finished. For example, this is okay: 'The parasite declined for two decades, but has increased in numbers in recent months.'

[RAHULS852]

Thanks Sage.
Got your point about "has ed".

Regards,
Rahul Singh

[Sage Pearce-Higgins]

You're welcome.