Final answer:
Synchondroses and symphyses joints are types of cartilaginous joints that are connected by cartilage, specifically hyaline cartilage for synchondroses and fibrocartilage for symphyses.
Step-by-step explanation:
Synchondroses and symphyses are types of cartilaginous joints where the bones are connected by cartilage. Specifically, synchondroses are connected by hyaline cartilage and are typically found in areas like the epiphyseal plates of long bones in children, allowing for bone growth. Symphyses, on the other hand, are connected by fibrocartilage and are commonly found between vertebrae and at the pubic symphysis. Both types of joints allow for only a limited amount of movement. Thus, the answer to the student's question, 'Synchondroses and symphyses joints are connected by _______,' is b) Cartilage.