What is a cluster?
a.) plasma emission from the sun b.) cosmic rays in the solar system c.) portion of space containing many planets d.) portion of space containing many galaxies

A cluster is D.) Portion of space containing many galaxies.

Hope this helps. Chao.

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

when the use of electricity burdens the fuse and miniarure circuit beakers and there is a possibility of a fuse then they automatically cut off the electricity supply to your homes and after you fix the problem u jzt switch it on and it continues the supply of electricity to ur homes