Which of the following statement is correct?

a. After an M&A deal is announced, going long the stock of company being acquired and shorting stock of acquiring company is called merger arbitrage

b. Long and short in matched equity portfolios of the similar size within a country is called long/short equity

c. Going long the undervalued equity and shorting overvalued equity is called distressed strategy

d. Investing in debt of companies in financial distress is called fixed-income arbitrage