Correct Answer - A
All the blocks will be having the same acceleration along the length of the string. So, Applying Newtons law along the string on A,B & C
`rArr 6g - 2g sin 30_(0) - 2g = (6+2 +2)a`
`rArr 3g = 10 a`
`rArr a = (3g)/(10)`
or `a = 3m//s_(2)`.