Acceleration of centre of mass problem

[coldblood]

Hi friends,
I have an issue in solving a Acceleration of center of mass problem.
Please Help me in solving this.
Thank you all in advance.

The problem is as:

https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-prn2/q71/s720x720/1395961_1432382973655475_777941089_n.jpg


Attempt:

https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-ash4/q82/s720x720/1381887_1432380636989042_263502974_n.jpg

Friends according to me the answer should be Option (b) but question says the answer is option (a).Please try to help me in this.
I will appreciate the help.

 

[NihalSh]

When you will convert your answer to vector form, the answer would match option (a). Because the vectors include the direction, so minus sign will not be shown. Assuming positive direction to be downwards, then $\vec{R}=-R$

 

[coldblood]

When you will convert your answer to vector form, the answer would match option (a). Because the vectors include the direction, so minus sign will not be shown. Assuming positive direction to be downwards, then $\vec{R}=-R$

Thanks NihalSh, I got that.
Thank for the help.