Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Drawbacks of technical analysis include which of the following?
Option A:It identifies changes in trends only after the fact.
Option B:Deviations from intrinsic value can persist for long periods.
Option C:It usually requires detailed knowledge of the financial instrument under analysis.

Answer: A