Which of the following is an unanswered question about life on earth? how long has life existed on earth? what were early forms of life like? did early life arise spontaneously or did it come from space? how does evolution occur?

The correct answer is option C, Did early life arise spontaneously or did it come from space?

There is no information regarding the arise of life on planet earth. No trace of fossils could clearly indicate the cause of origin of first species. However, the first species on the planet is only the oldest species found till date, it is not sure till today whether it is the oldest or there exists few more old species which have not been explored yet.

true skin; another name for the dermis. lies directly beneath the epidermis and is often referred to as the true skin. outermost layer of epidermis, consisting of dead cells.