Which of the following is a food source rich in vitamin D?

Cod liver oil is a well-known source of vitamin D, making it the correct choice. Vitamin D is crucial for maintaining healthy bones and plays a vital role in calcium absorption. It can be challenging to obtain sufficient vitamin D from food sources alone, but cod liver oil is particularly rich in this nutrient. In addition to vitamin D, it also contains omega-3 fatty acids, which contribute to heart health.

The other options do not provide significant amounts of vitamin D. Carrots, while nutritious and high in beta-carotene, do not contain vitamin D. Almonds are healthy nuts that provide vitamin E and fats, but they lack vitamin D as well. Spinach is known for its rich content of iron, vitamins A and K, but it also does not contain vitamin D. Thus, cod liver oil stands out as the superior food source for this essential vitamin.