The correct answer is C. I, II, III and IV only.
All four statements are true regarding the benefits of irrigation in crop production:
I. Seeds need moisture to germinate - Irrigation provides the necessary moisture for seed germination. II. Plants can absorb nutrients mostly in dissolved forms - Irrigation helps dissolve nutrients in the soil so that they can be absorbed by plants. III. It protects crops from frost - Irrigation can help create a humid microclimate that may protect against frost damage. IV. It improves soil texture - Proper irrigation practices can enhance soil structure and texture, making it more conducive to crop growth.
Therefore, all four points are valid contributions of irrigation in crop production.