As asked in the question, the "person with scientific temperament" is for any person and not just a Piscean. Having scientific temperament fundamentally implies that astrological forecasts are not to be believed in as science does not really recognise astrology. 
SO for a person who has a strictly scientific outlook, the given statement has no original value from a forecast perspective as the statement is applicable to anyone at ant given point of time.

No problem, you are welcome.

Thanks sir it was really helpfull

Thanks. I understood my mistake

Hi
In this question, we have to think from the perspective of a scientific person. Such a person would look to debunk pseudo-sciences like astrology in two ways.
1. Find mistakes or inaccuracies in prediction.
2. If the above is not possible, then dismiss the prophecy as a generally known fact or principle which anyone with commonsense could have predicted.

Here the prediction says work hard leads to success, which is a general formula applicable to all.
Hence the answer is Option D.

Now for the other options:
Options A B and C: These would require believing in the astrological concept that people can be classified solely based on their date of birth which is illogical from a scientific point of view.
Option E: A scientific person would never consider astrology to be based on research.
Hence we can eliminate all four of these options.

Why is it considered that the person with scientific temperament will debunk the astrology wherein astrology itself is akso science this question seems it is not complete in itself as person with scientific if believes that astrology is true would go with option d as scientific temperament always believe in research

Hi
The idea here is that no valid scientific community has accepted Astrology to be a real branch of science. Hence we cannot equate the two together.

Hi,
The person possessing the scientific temperament will say "the forecast for people belonging to the sun sign puts forth a general principle which applies to all persons."

As the statement is, in general, true for anyone

"The efforts you make could set the stage for some new opportunities later on. Keep ahead of the opposition by using your imagination and by being original."

Hi Anjali,
The question asks "For a person possessing scientific temperament" 
A person of science will more likely or not question such statements. Additionally on reading the excerpt we can see that if we had read that line out of context we would have assumed that it is applicable for anyone.This is why Option D is correct.
Hope this helps!

Hi Dinesh,
Since the person is of scientific temperament he's unlikely to believe that some people are affected by certain changes in the position of stars than others which is why he's likely to believe that it is generic statement that is applicable for everyone.
Hope this helps!

Hi Suryaprakash,
Exactly as you mentioned since he is a man of scientific temperament he is wont believe in astrology and hence would say that the statement the astrologers can make can be true for everyone (generic statement).
Hope this helps!