Well it have to be D because 32 and 20 can not go into 64 to 40 because 32 times 64 is 2048 and 64 times 20 is 1280 and if it was 40 times 32 and 20 it will still be higher. I HAVE FAITH IN YOU.
Let

denote the random variable for the weight of a swan. Then each swan in the sample of 36 selected by the farmer can be assigned a weight denoted by

, each independently and identically distributed with distribution

.
You want to find

Note that the left side is 36 times the average of the weights of the swans in the sample, i.e. the probability above is equivalent to

Recall that if

, then the sampling distribution

with

being the size of the sample.
Transforming to the standard normal distribution, you have

so that in this case,

and the probability is equivalent to

The ratio of 2:9 has to be 2:9 do to the fact you can't simplify the fraction 2/9.
Hoped I helped.
13 m is the volume of the prism