"To identify, in a sample, the protein against which you have an antibody, the best technique to use would be blotting."

Western blotting

Explanation:

The western blotting is a technique invented in 1979 which is nowadays used to analyse the protein sequences.

The western blotting technique involves the transfer of the sample from the gel to the blotting sheet or nylon membrane and immunoglobulins or antibody against the antigen. The antigen-antibody interactions allow the identification of a specific protein from the protein sample.

Thus, western blotting is the correct answer.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.