A student has been assigned to perform five tasks-A, B, C, D. & E. The tasks are to be done in a particular order, which conforms to the following conditions: A must be done earlier than C. B must be done earlier than D. E cannot be the fifth task done. In case B, D and E are to be done one after the other in the given order, the two positions from first to fifth in which A could possibly be done are