Based on the lectures, what is one primary difference between SEM and SEO?

a$.$ Marketers pay the search engine for SEM results, but not SEO results.

b$.$ SEM is better for marketing consumer products, while SEO is better for marketing business products.

c$.$ Marketers pay the search engine for SEO results, but not SEM results.

d$.$ Marketers can use analytics to measure SEM performance, while SEO performance cannot be measured with analyt