Chefs work in a small kitchen area, moving quickly. They need to keep up with a fast pace and adapt to meet the needs of customers. Chefs face pressure to satisfy customers, but they also get to be creative and experiment with new foods. Dancers work on large stages, moving around. They constantly have to perform for an audience and need to be comfortable in front of large groups of people. Dancers cannot be shy.

Both careers allow for creativity and self-expression. Both face pressure from their audience, but chefs tend to work in one place, while dancers may perform on many stages in many places. Chefs may not see their audiences directly, but dancers definitely do.

What makes this paragraph an example of subject-by-subject writing?

Being a chef is discussed, and then being a dancer is discussed, and then they are compared.
Dancing is discussed around one subject, and being a chef is discussed around another.
Dancing and cooking are compared around the same criteria as they are discussed.
Dancing and cooking are compared, and then the writer arrives at a conclusion.