Brian bought shares in National Lawn Architecture at $$10$ per share because it had dropped from $$15$ in a declining market. Since then, the price of National Lawn has dropped down to $$8$ per share. Brian intends to buy more shares because he believes that the stock is significantly undervalued and the market will rebound. He is basing this investment strategy completely on this price behaviour. Which of the following biases is Brian exhibiting?

a$.$ Anchoring

b$.$ Status quo

c$.$ Loss aversion

d$.$ Endowment