between D and E, would go with E.

the live shows seem to be targetted at diverting excess crowds at lunch and attracting enough for supper or in other words just the right capacity/optimal utilization of the restaurant

substituting numbers could be an option let upstream, downstream distance be 10m, speed of the man be 5m/s, speed of stream be 1m/s total time taken(x): upstream time+downstream time= 10/(5-1)+10/(5+1)=25/6~4.1 total time taken in still water with same distance and speed (y): 20/5=4 => x>y hence A

would go with D, as it gives a reason why there might be a positive correlation between the decline in the number of alligators and the fish

A, B, C and E are out of scope.

we need the past perfect to indicate the earlier of two past events. #1 the safety commission meeting had happened before the bridge collapsed. so we use the "had been" to indicate that this happened before the collapse. "preliminary" doesnt by itself indicate which event happene...

C for parallelism of participles

stem cells can be directed to...., used to test and studied to gain...

"such an end " in C would mean an end similar to finding ancient Troy, but the intended meaning is finding ancient troy is the end itself.

would go for B, all others are kind of out of scope. they do not address the effect on the cigarette smokers.

i guess stmnt 2 is insufficient as it doesnt mention x, so we cant answer the question: is x>y