DSE 2014 Question 7: General equilibrium and exchange economies

Consider an exchange economy with two agents, 1 and 2, and two goods $X$ and $Y$. Agent 1's endowment is $(0,10)$ and Agent 2's endowment is $(11,0)$. Agent 1 strictly prefers $(a,b)$ to $(c,d)$ if $a>c$, or $a=c$ and $b>d$ (lexicographic, $X$ first). Agent 2 strictly prefers $(a,b)$ to $(c,d)$ if $\min\{a,b\}>\min\{c,d\}$. Which of the following changes makes $(p_X,p_Y)=(1,0)$ a competitive equilibrium price vector?