On which day would the intensity of isolation at Kingston, New York, most likely be the greatest

A. March 21
B. June 21
C. September 23
4. December 21

i·so·la·tion 
–noun
1. an act or instance of isolating.
2. the state of being isolated.
3. the complete separation from others of a person suffering from contagious or infectious disease; quarantine.
4. the separation of a nation from other nations by isolationism.
5. Psychoanalysis . a process whereby an idea or memory is divested of its emotional component.
6. Sociology . social isolation.
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in·so·la·tion
–noun
exposure to the sun's rays, especially as a process of treatment.
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From your phrasing of the question, you are referring to the second definition, which is for "insolation".

The intensity of solar radiation in Kjngston, New York is likely to be greatest on "B. June 21" <====== Answer!

I hope this is helpful.

The isolation will never change, except if you build a new highway or airport.

However the insolation would be greatest at the summer solstice, on or about June 21 every year.