What do scientists think produces earth’s magnetic field?

John recently received his semester grades and found that he had failed two courses. he says the reason he failed the two courses is that they were taught by female professors. john believes that women are really not smart enough to teach at the college level. in this example, the female professors are a) spacegoats and being blamed for john's grades b) being discriminatory toward john c) probably not smart enough to teach in a college d) prejudiced against john because he is male