Answer: b: Bend the arm at the elbow with the back straight.
Step-by-step explanation:
The person should stand straight with a dumbell in each of the hand particularly at the length of the arms. The elbow should lie close to the torso. The person should rotate the palms of the hands until the hands face forward. This will be like starting position for this exercise. Then upper arms should be kept stationary. The person should exhale and curl the weights during this process the biceps also contracts. The entire body should be kept straight during this exercise.