I've played the London System for about 3 months and am liking it alot, however I have run across several games where Black played a weird, but good, move early in the opening, c5.
1. d4 d5 2. Bf4 c5
Here, c5 is threatening to take on d4, a key position in the London System.
How does one play with a threatening move such as this with the London System, or what style of play has generally come of this move.
My last question, when Black plays c5, does this generally spell the end for typical London System lines, if played out with typical responses?