Which statement best differentiates cell crawling from chemotaxis?

• A. Cell crawling requires energy, while chemotaxis is a passive process.
• B. Cell crawling occurs only in muscle cells, while chemotaxis occurs in all cell types.
• C. Cell crawling involves movement in response to chemical signals, while chemotaxis does not.
• D. Cell crawling is a physical movement across a surface, while chemotaxis is movement in response to chemical gradients.

Answer: (D)