Correct answer is (c) property
The explanation is: The value of transition-duration specifies a length of the transition effect. The delay in transition effect is give by delay value. The value of transition-function specifies transition acceleration. The value of property targets the CSS property to which transition effect should be applied. The property should be height, color, width, background etc. But if the value is not explicitly specified, it will take all as the default value, and will be applied to all the properties.