Aflorist wanted to investigate whether a new powder added to the water of cut flowers to keep the flowers fresh longer than just water alone. for a shipment of roses that was delivered to the store, the florist flipped a coin before placing each rose in its own individual container with water. if the coin landed heads up, the rose was placed in water with the new powder; otherwise, the rose was placed in water alone. which of the following is the best description of the method used by the florist?

a. a census, because all roses are assigned to a container
b. an experiment with a completely randomized design
c. an experiment with a blocked design, with blocking by type of water
d. an experiment with a matched-pairs design
e. an observational study