The correct answer is B. Fossil data
Step-by-step explanation:
It is well known in science and biology that most of the species that ever lived have disappeared by known and therefore methods need to be used to know their existence, appearance, and features. One of the main and common methods for doing this is the use of fossil data or the information provided by fossils, which are remains or traces about an organism including bones, prints, hair, DNA, etc.
Because of this by collecting fossils and analyzing them it is possible to have realistic information about early animal species and their features. Also, others such as morphological or embryological data are mainly used to study living species or early animals just after collecting a lot of information about them usually through fossils. Therefore, the type of data primarily used to determine the existence and appearance of early species is fossil data.