Blood is a(n) ________ tissue because it has a _________. a. connective; gap junction b. muscular; ground substance c. epithelial; gap junction d. connective; ground substance

There are four types of tissues: connective, muscular, epithelial, and nervous. Each has its own specific characteristics and functions. Blood is a specialized bodily fluid that circulates through the body, delivering necessary substances and removing waste products. We need to identify which tissue type blood belongs to.

a. Connective tissue is a type of tissue that supports, connects, or separates different types of tissues and organs in the body. It contains cells, fibers, and a ground substance (a non-cellular component). Blood fits into this category. b. Muscular tissue is responsible for movement and is composed of muscle fibers. Blood is not a type of muscular tissue, as it does not have muscle fibers and is not responsible for movement. c. Epithelial tissue forms the outer layers of organs and structures and is involved in absorption, secretion, and protection. Blood is not epithelial tissue, as it does not form any outer layers or participate in absorption or secretion activities. d. Connective tissue is once again presented as an option, but this time the reason given is "ground substance." Ground substance is a non-cellular component in connective tissue that is involved in the support and organization of the cells and fibers.

Based on our analysis of the options, the correct answer is: Blood is a(n) connective tissue because it has a ground substance. So, the correct option is \( \boxed{d} \).