Which of these statements is $($are$)$ TRUE? I. To buy and hold is to purchase stocks and keep them for the long run regardless of what prices do in the short run. II$.$ If you accept the efficient market hypothesis and the value of diversification, your best trading strategy is to buy and sell. III. According to finance economists, the safest stocks are those that move up and down in harmony with the market.

I and III only

III only

II only

I only