Statement 1 states that spinach is a good source of vitamin A, which is correct. Spinach is indeed rich in vitamin A, which is important for healthy vision, immune function, and cell growth.

Statement 2 states that excess vitamin D in the diet promotes high calcium absorption. This is also correct. Vitamin D helps the body absorb calcium from the diet, which is vital for strong bones and teeth.

Statement 3 suggests that one of the causes of joint pain is vitamin C deficiency. This is incorrect. Vitamin C deficiency is associated with scurvy, which can cause symptoms like swollen and painful joints, but it is not the sole cause of joint pain.

Statement 4 states that diarrhea is one of the symptoms of pellagra, which is correct. Pellagra is a condition caused by niacin deficiency and is characterized by symptoms such as diarrhea, dermatitis, and dementia.

Therefore, option 4 is the correct answer as it includes all the correct statements.