In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[Q]: Antigens illicit the release of what in the body?, Context: The humoral (antibody) response is defined as the interaction between antibodies and antigens. Antibodies are specific proteins released from a certain class of immune cells known as B lymphocytes, while antigens are defined as anything that elicits the generation of antibodies ("anti"body "gen"erators). Immunology rests on an understanding of the properties of these two biological entities and the cellular response to both.
[A]: antibodies


[Q]: what race is mentioned first?, Context: NASCAR (headquartered in Daytona Beach) begins all three of its major auto racing series in Florida at Daytona International Speedway in February, featuring the Daytona 500, and ends all three Series in November at Homestead-Miami Speedway. Daytona also has the Coke Zero 400 NASCAR race weekend around Independence Day in July. The 24 Hours of Daytona is one of the world's most prestigious endurance auto races. The Grand Prix of St. Petersburg and Grand Prix of Miami have held IndyCar races as well.
[A]: Daytona 500


[Q]: What led to the result that observers in relative motion measure different elapsed times?, Context: In non-relativistic classical mechanics, Newton's concept of "relative, apparent, and common time" can be used in the formulation of a prescription for the synchronization of clocks. Events seen by two different observers in motion relative to each other produce a mathematical concept of time that works sufficiently well for describing the everyday phenomena of most people's experience. In the late nineteenth century, physicists encountered problems with the classical understanding of time, in connection with the behavior of electricity and magnetism. Einstein resolved these problems by invoking a method of synchronizing clocks using the constant, finite speed of light as the maximum signal velocity. This led directly to the result that observers in motion relative to one another measure different elapsed times for the same event.
[A]:
a method of synchronizing clocks