The correct answer is: A. weak-form EMH.
The random walk hypothesis is a theory that stock prices move randomly and cannot be predicted. This is in contrast to the efficient-market hypothesis (EMH), which states that stock prices reflect all available information and cannot be systematically beaten by investors.
The weak-form EMH is a subset of the EMH that states that past prices cannot be used to predict future prices. This is because all past information is already reflected in current prices.
The random walk hypothesis is most closely related to the weak-form EMH because it states that stock prices move randomly and cannot be predicted using past prices.
The semi-strong form EMH states that current prices reflect all publicly available information. This means that investors cannot use publicly available information to earn excess returns.
The strong-form EMH states that current prices reflect all information, both public and private. This means that even investors with access to private information cannot earn excess returns.
I hope this helps! Let me know if you have any other questions.