$A$ glass tube of uniform internal radius has a valve separating two identical ends. Initially,the valve is in a tightly closed position. End $1$ has a hemispherical soap bubble of radius $r$. End $2$ has a soap bubble with a radius of curvature $R$ $(R > r)$ as shown in the figure. Just after opening the valve,

• A
  air from end $1$ flows towards end $2$. No change in the volume of the soap bubbles.
• B
  air from end $1$ flows towards end $2$. Volume of the soap bubble at end $1$ decreases.
• C
  no change occurs.
• D
  air from end $2$ flows towards end $1$. Volume of the soap bubble at end $1$ increases.