To determine the net exports for the country, we can use the savings-investment identity, which states:
\[ \text{Net Exports} = \text{Savings} - \text{Domestic Investment} \]
Substituting the given values:
\[ \text{Net Exports} = 60 \text{ million} - 40 \text{ million} = 20 \text{ million} \]
Therefore, the correct answer for net exports is:
a. $20 million.