Answer:
B) Selection against cross breeds and assortative mating. 
 C) Ploidy level movements 
 Step-by-step explanation:
- Sympatric speciation is typically known as troublesome determination, a kind of common choice wherein two particular varieties in an attribute are supported rather than a transitional type of the characteristic. 
- This speciation mostly happens through polyploidy, in which a posterity or gathering of posterity will be delivered with double the ordinary number of chromosomes.