Given the Following Ricardo-Type Table Showing the Amount of Labor

Multiple Choice

Given the following Ricardo-type table showing the amount of labor input required to produce one unit of output of each of the two goods in each of the two countries:
$\begin{array} { l l l } &\underline{ \text { Wheat} } &\underline{ \text { Clothing} } \\\text { United Kingdom } & 6 \text { days } & 5 \text { days } \\\text { United States } & 4 \text { days } & 3 \text { days }\end{array}$
Suppose that the U.S. wage rate is $60 per day and that the exchange rate is $2 = £1 (or £0.5 = $1) . In this situation, the lower limit for the U.K. wage rate in order to have two-way trade would be __________ per day.

A) £18
B) £20
C) £45
D) £50