Verify the truth table of RS, JK, T and D flip-flops using NAND & NOR gates

Which of the following is correct for a gated D-type flip-flop?
A basic S-R flip-flop can be constructed by cross-coupling of which basic logic gates?
The truth table for an S-R flip-flop has how many valid entries?
The flip-flops which has not any invalid states are _____________
Both the J-K & the T flip-flop are derived from the basic _____________