Light waves will bend when passing from one transparent substance to another unless:

a. constructive interference occurs.

b. destructive interference occurs.

c. the light hits the substance at an angle of 60 degrees.

d. the light hits at an angle of 90 degrees.

Consider a file currently consisting of 200 blocks. assume that the file control block (and the index block in the case of indexed allocation) is already in memory. calculate how many disk i/o operations are required for contiguous, linked, and indexed (single-level) allocation strategies, for each of the conditions listed below. in the contiguous-allocation case, assume that there is not room to grow at the beginning but there is room to grow at the end. also assume that the block information to be added is stored in memory.