Jack and his family have developed a successful business selling a liquid spray fertilizer to farmers. The fertilizer consists of rich, organic, composted material. Recently, Organic Seed, a national seed company, has been marketing a powdered chemical fertilizer to its customers. Organic$$s fertilizer is less expensive than Jack$$s product. Organic$$s efforts are an example of the $\_\_\_\_\_\_\_\_$ in Porter$$s model for industry analysis $($five forces model$).$

a$.$rivalry among competitors

b$.$buyers$$ cooperation

c$.$threats of suppliers$$ products and services

d$.$power of the suppliers