Your field would have to be nested:
{ If { Dropdown1 } = "A" "You chose A""{ IF { Dropdown1 } = "B" "You chose B""{ IF { Dropdown1 } = "C" "You chose C""{ IF { Dropdown1 } = "D" "You chose D""" }" }" }" }
I would suggest linking your dropdown CC with another CC. This may offer some help:
http://gregmaxey.com/word_tip_pages/linked_content_control_dropdown_list.html