Mammals Cannot Produce Polyunsaturated Fatty Acids

Mammals cannot produce polyunsaturated fatty acids. How is it then that the lard obtained from beef fat contains up to 10 percent polyunsaturated fatty acids?

A) Microbes within their gut transformed them into polyunsaturated fatty acids.
B) These unsaturated are a side effect of growth hormones in their diet.
C) These polyunsaturated fatty acids came from the cow's vegetarian diet.
D) These polyunsaturated fatty acids come from the processing of the lard.