Marco and Yara are discussing connective tissue and Marco states that blood can't be a connective tissue because it's a liquid. Yara claims that blood is a specialized connective tissue with a fluid ECM. Who is right and why?

• A. Marco because blood doesn't have a ground substance so it can't be connective tissue. 
• B. Yara because the viscosity of the ground substance can vary from low to extremely high. 
• C. Marco because connective tissue only includes connective tissue proper. 
• D. Yara because all liquids found in the body are connective tissue.