Explanation:

- 4:2:1: This is a commonly recommended NPK ratio for balanced fertilization. It supports overall plant health, with nitrogen for leafy growth, phosphorus for roots, and potassium for disease resistance.

- 2:4:1: A higher phosphorus content is unusual for general use. It's more suitable for plants in their flowering stages or root development.

- 4:1:2: This ratio focuses more on nitrogen, which could promote leaf growth but might not be ideal for flowering or fruiting plants due to low phosphorus content.

- 8:3:2:1: This ratio includes a fourth component, making it atypical for standard NPK classifications.