Which of the following scenarios would produce the Doppler Effect? Check all that apply.

A moving sound source (such as an airplane passing overhead)

A moving observer of a source (such as a person running past a loud
stereo)

A moving source and moving observer (such as kids chasing an ice
cream truck that is playing music)

A non-moving source and non-moving observer (such as person
watching television on a couch)

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.