Which of these doubles can be made by Responder, whether on the first round or later?
A, D, E are all possible. Negative doubles are doubles on the first round of the bidding by responder and typically focus on the other major.
Maximal doubles are made on auctions where a fit is found:
| West | North | East | South |
|---|
| | 1 | Pass | 1 |
2 | 2 | 3 | Dbl |
This double invites game (since the opponents have bid one below your suit on the 3-level).
There are a variety of penalty auction doubles, but one of the fastest is opening bid, 1NT overcall, double by responder.
Support doubles are only made by the opening bidder to show 3-card support for responder's suit.
Responsive doubles are made, counterintuitively, by the advancer:
| West | North | East | South |
|---|
1 | Dbl | 2 | Dbl |