Force F1 acts on a particle and does work W1. Force F2 acts simultaneously on the particle and does work W2. The speed of the particle does not change. Which one of the following must be true?a. W1 is zero, and W2 is positiveb. W1 = - W2c. W1 is positive, and W2 is positived. W1 is positive, and W2 is zero