When home country is a large importing country, the optimal tariff should be larger than $0.$

A$.$ YesB. NO

Suppose Japan and China have $10,000$ hours of labor supply per month. In Japan, it takes $10$ hours to produce a unit of computer and $4$ hours to produce a pair of shoes. Whereas in China, it takes $20$ hours to produce a unit of computer and $6$ hours to produce a pair of shoes. Which country has the comparative advantage in producing computers?