Could you please answer question 5, thanks

Question 5 (1 point) Which of the following should happen when a country opens up to trade with another country in the internal economies of scale model with symmetric/identica firms? O marginal products of labour decrease due to increased usage of resources in production There will be fewer firms in the world post-trade, compared to the number of pre-trade firms in the two countries combined The number of firms/varieties avaiable to consumers increases The highest cost firms will be forced to exit More than one choice is correct