Select the option which is related to the third word in the same way as the second word is related to the first word. (The words are to be treated as meaningful words and not related to each other on the basis of number of letters/consonants/vowels in the word.)

Scientist : Laboratory :: Astronomer : ?

Logic : Professional : Workplace associated

So,

• Scientist works in a laboratory.

Similarly,

• Astronomer works in an observatory.

Hence, "Observatory" is the correct answer.

Additional Information 

• Profession → A paid occupation, especially one that involves prolonged training and a formal qualification.
• University → A professor works in an university.
• Environment → the surroundings or conditions in which a person, animal, or plant lives or operates.
• Observatory → It is a place or building equipped and used for making observations of astronomical, meteorological, or other natural phenomena.