Yah isnt that obvious? Gasses mix everywhere in all proportions.
D is the correct answer, assuming that this is the special case of classical kinematics at constant acceleration. You can use the equation V = Vo + at, where Vo is the initial velocity, V is the final velocity, and t is the time elapsed. In D, all three of these values are given, so you simply solve for a, the acceleration.
A and C are clearly incorrect, as mass and force (in terms of projectile motion) have no effect on an object's motion. B is incorrect because it is not useful to know the position or distance traveled, unless it will help you find displacement. Even then, you would not have enough information to use a kinematics equation to find a.
Systemic circulation is between the heart and the rest of the body. Therefore arteries and veins are needed.
Given the temperature, we can tell if the substance is cold or not relative to the reference temperature. For example, compared to the substance having a temperature of 15 degrees C, the substance is colder and it is hotter from the substance of temperature lesser than 12 degrees C.
If light travels from oil to water at an angle, what happens to the direction of the light ray in water with respect to the normal, is it moves away from the normal.