Answer: B. Flow folds develop.
C. Foliations develop.
Explanation: Flow folding is termed as the the folds that tend to occur in the rocks that are incompetent in nature .The weak rocks can flow in any direction and does not remain attached due to continental collision.
Foliation is development of the layers in the rocks e.g.-metamorphic rocks.The rocks starts to form sheet-like structure and forming coat to cover each layer after getting collided.
Other options are incorrect because cleavage plane is the mineral breakage into the plane with smooth surface and phenocrysts is a clear crystal containing igneous rock which don't get carried away due to collision.Thus the correct option is option(B) and (C).