Exemplars are what type of sample?
a.
forged
b.
questioned
c.
authentic
d.
counterfeit

Exemplars or "standards", or "handwriting samples" are authentic samples of handwriting used to establish a judgment about the authenticity of certain handwriting by somebody called "the examiner" when a court case starts, and they are compared with a "Questioned document" or "Questioned writing" or "suspect document" which are documents with questionable authenticity; Thereby (B).

C.  Authentic

Explanation:

Exemplars are the handwriting samples, machine printing samples such as printers and typewriters, these are the legally admissible samples which are authentic. These are the samples which can be used for the comparison with the questioned document. These are used by the question document expert to frame the opinion and prove that in the court of law.

the answer is minerals.