It is how bright is is t the observer on earth...so wuld be c!!
this any help?
D. 99% of all living things that have ever existed are now extinct
Antibodies, also called immunoglobulins, are proteins manufactured by the body that help fight against foreign substances called antigens. When an antigen enters the body, it stimulates the immune system to produce antibodies. (The immune system is the body's natural defense system.) The antibodies attach, or bind, themselves to the antigen and inactivate it.<span>
Read more: <span>http://www.scienceclarified.com/Al-As/Antibody-and-Antigen.html#ixzz4YlY105DD</span></span>