Read the following context and choose the best option to answer the question.
Context: Taking Lexapro , an SSRI , was like firing an arrow at the same spot on the seratonin target over and over . It works for awhile , but eventually you ' ve shot arrows at the one spot for so long there 's nothing left to hit . That part of the target is just a hole . If you switch to a different SSRI it aims at another part of the seratonin target and can help alleviate depression symptoms .
Question: What is Lexapro ?
Options: 
A. Seratonin .
B. None of the above choices .
C. An antidepressant .
D. An arrow .


C