Given a scientific passage and an answer, generate a question for the given answer.

Example Input: Passage: The rock of the mantle is mostly peridotite. Peridotite is formed of crystals of olivine (green) and pyroxene (black). Answer: peridotite
Example Output: The rock of the mantle is mostly what?

Example Input: Passage: A single-replacement reaction is one in which an element replaces another element in a compound. An element is in either the solid, liquid, or gas state and is not an ion. The example below shows the reaction of solid magnesium metal with aqueous silver nitrate to form aqueous magnesium nitrate and silver metal. Answer: single-replacement reaction
Example Output: In this type of reaction, an element replaces another element in a compound, and the element is in any state of matter but is not an ion?

Example Input: Passage: 10.9 Development and Regeneration of Muscle Tissue Muscle tissue arises from embryonic mesoderm. Somites give rise to myoblasts and fuse to form a myotube. The nucleus of each contributing myoblast remains intact in the mature skeletal muscle cell, resulting in a mature, multinucleate cell. Satellite cells help to repair skeletal muscle cells. Smooth muscle tissue can regenerate from stem cells called pericytes, whereas dead cardiac muscle tissue is replaced by scar tissue. Aging causes muscle mass to decrease and be replaced by noncontractile connective tissue and adipose tissue. Answer: scar tissue
Example Output:
While smooth muscle tissue can regenerate from stem cells called pericytes, dead cardiac muscle tissue is replaced by what type of tissue?