1) Continental drift is caused by sea bed expanding and the reason for this seabed expanding is volcanic eruptions which happens in the Atlantic ocean.
So seabed expansion between americas and africa - eurasia can be understood. What's the reason for seabed expansion between Africa and Australia-India ?
2) In the theory of continental drift, it is stated that continents had to plow through the seabed. what force would cause the movement of such a large body like Indian plate ? If seabed expansion is causing the continental drift, then continents dont have to move, as its seabed itself which is expanding and causing the movement, right ? So why would continents move ?
3) If seabed is expanding between two continents, does it mean that its contracting at some other location by the same amount in the earth's crust ?
1)Continental drift is caused by convection currents in the mantle, sea floor expansion is caused by the continental drift. The sea floor expansion between the Africa and Australia and India. Is caused by the African and the Indo-Australian Plates moving apart, creating the Central Indian Ridge, which is like the Mid-Atlantic Ridge.
2+3)Tectonic Plates are what move, most of the plates have both continent and ocean on them. When the convection currents move these plates, the plates then move apart from each other but that means that the plates also have to collide with other plates for example the Euraisan plate is moving away from the North American plate, and therefore in order to move the Eurasian plate must subduct or push-up/buckle another plate (creating the himalaya's). I'm order for new crust to be created crust must also be destroyed at the same rate elsewhere or the earth would buldge.
hope this answers your questions