Answer:
a rational investor would short company A's shares and long company B's shares.
Step-by-step explanation:
Company A's shares are overvalued.
A share is overvalued when its intrinsic value is less than its price
Company B's shares are undervalued.
A share is undervalued when its intrinsic value is greater than its price
It is expected that the price of company's A's share would fall. Investors that are holding this company's share would lose.
On the other hand, it is expected the the price of company B's shares would rise. Investors holding this company's share would gain from the increase in price.
Thus, a rational investor would short short company A's shares and long company B's shares.