In Regards to the Quantity of Labour Supplied, What Does

In regards to the quantity of labour supplied, what does the substitution effect indicate about the relationship between the wage rate and the opportunity cost of leisure?

A) At a higher wage rate, the opportunity cost of leisure decreases making leisure less expensive.
B) At a higher wage rate, the opportunity cost of leisure increases making leisure less expensive.
C) At a higher wage rate, the opportunity cost of leisure increases making leisure more expensive.
D) At a higher wage rate, the opportunity cost of leisure decreases making leisure more expensive.