单项选择题
Spary the plate with phloroglucinol solution;the bands due to cinnamaldehyde and o-me-thoxy cinnamaldehyde are yellowish brown and violet respectively．In the description of the experimental chromatogram which of the following is correct（）
A．代表桂皮醛的带为紫色
B．代表O-甲氧基桂皮醛的带为黄棕色
C．代表桂皮醛和O-甲氧基桂皮醛的带为黄棕色至紫色
D．代表O-甲氧基桂皮醛的带为紫色，代表桂皮醛的带为黄棕色
E．以上都不对