People, such as pilots, who have to move quickly from lighted surroundings to night darkness use red light illuminatin. This is because
red light slows down dark adaptation.
red light is a stimulating color and tends to keep pilots and military personnel
aroused and alert.
the cones are insensitive to red light.
the rods are insensitive to red light.

the rods are insensitive to red light.

Explanation:

People, such as pilots, who have to move quickly from lighted surroundings to night darkness use red light illumination because human eye is less sensitive to longer wavelength ( rhodopsin in rods cells of eye).Using red goggles,the cones can receive enough light to provide photopic vision. Whereas rods are less sensitive to longer wavelength (red light).So, the crew members remains dark adopted.

Hence, (d) is the correct answer.

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.