Which method of generating electrical energy results in electricity that is relatively easily distributed to where it is needed, when it is needed? a. using coal-fired power plants b. using tidal flow generators c. using wind turbines d. using solar cells

Possibly A. after all, the grid transmission system was designed at a time when electricity was generated using burning coal to heat water to steam to drive massive electrical dyamos which fed the grid which fed the houses. 
Wind needs the weather to be windy.
Solar cells need some sunshine
tidal power needs coastal areas and very large areas at that.