Twin type has less to do with what twins look like and more to do with how they formed.
Identical, or monozygotic, twins form when a single fertilized egg splits and develop as two babies in the uterus. Identical twins originate from the same combination of cells and have the same genetic origin. They are ALWAYS the same sex, two girls/two boys. They may look very similar and it may be difficult to tell them apart.
Fraternal, or dizygotic, twins are two individuals from the same pregnancy who from TWO SEPARATE eggs fertilized by TWO SEPARATE SPERM. The genetic similarity between fraternal twins is the same as any two siblings, about 50 percent. They can be boys, girls, or one of each.
Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that the friction force on two boxes is given as



Now we know by Newton's II law

so we have




Part b)
For block B we know that net force on it will push it forward with same acceleration so we have




Part c)
If Alex push from other side then also the acceleration will be same
So for box B we can say that Net force is given as




The change in pressure measured across a given distance called a Pressure Gradient. The pressure gradient creates a net force that is directed from higher to lower pressure and is called the Pressure Gradient Force. ... As air increases in velocity, it is deflected by the Coriolis Force.