Given a scientific question, generate a correct answer to it.
--------
Question: What fertilizes an egg during sexual reproduction?

Answer: sperm

Question: What amazing machines smash particles that are smaller than atoms into each other head-on?

Answer: particle accelerators

Question: After an adaptive defense is produced against a pathogen, typically plasma cells first secrete immunoglobin, which constitutes about ten percent of all what?

Answer:
antibodies