Read the paragraph.

be wary of any individual who tries to sell you a device or pill that is promised to you easily lose weight or cure some illness. chances are good that this person is a charlatan who knows no more about fitness or disease than you do and is out to exploit the desire for quick fixes. remember that there are few, if any, quick fixes in matters of health.

what is a "charlatan"?

a. an amateur
b. an ignoramus
c. a fraud
d. a felon

A charlatan is a fraud (option C), as this word describes someone who intends to deceive others by claiming he/she has certain qualities or accomplishments, and therefore, be able to persuade people to do what he or she wants or convince them of something.

An amateur is someone inexperienced, so this option is not possible. An ignoramus is an ignorant; a charlatan can be considered an ignorant, but he/she has an intention (deceiving) and in this case, he/she somehow knows what they are doing.

A felon is someone who commits a felony (crimes more serious than misdemeanors). This option is not possible because deceiving others is a misdemeanor.