Consider the Following to Answer the Question(s) Below

Multiple Choice

Consider the following to answer the question(s) below.
KiPLEX manufactures plastic pipes. KiPLEX piping is a less expensive alternative to copper piping. BPLEX's marketing department wants to determine plumbers' satisfaction with KiPLEX piping. To do this, they plan to survey plumbers who purchase KiPLEX pipes on regular basis.
-Office of the KiPLEX marketing department is located next to a large construction site. The marketing department employees ask everyone who enters or leaves the construction site what they think about their product. This sampling method is called

A) simple random.
B) stratified.
C) cluster.
D) systematic.
E) convenience.