Consider the following queue execution eng(1) eng (3) eng(2) eng(X) deq(2) deg(1) deg(4) (a) What possible value(s), if any, could X be such that this execution would lineariz-able? (b) Given what you determined above, in what order does a linearizable execution occur? You may simply number the diagram (c) Label all periods of quiescence on the diagram. How many are there? You may omit the period before and after the execution