Which of the following statements is true? Select one:
O a. A vector can have positive or negative magnitudes.
O b. A vector's magnitude cannot be more than the magnitude of one of its components.
Oc. The magnitude of a vector cannot be zero unless all of its components are zero.
O d. If the x-component of a vector is smaller than its y-component then that vector is in the opposite direction to its y- component.