Correct option is A. 2,3,7
A) $$425\times 136=425\times (6+30+100)$$
[Distributivity of multiplication over addition]
Hence, 3
B) $$2\times 49\times 50=2\times 50\times 49$$
[Commutative under multiplication]
Hence, 1
C) $$80+2005+20=80+20+2005$$
[Commutative under addition]
Hence, 2