IMO A

let x = the number of shares of stock
let T = total

it went from X/T to (X+some value)/T since the ratio has increased.

B does not give us sufficient information b/c total number of shares of stocks and bonds increased.

Bonds might have increased and the stock might have stayed the same or stock might increased and bonds might have stayed the same or both bonds and stock might have increased.

IMO C
Let number of shares is s and number of bonds is b

a: the ratio of the number of shares of stock to the total number of shares of stocks and bonds in Ruth's portfolio increased

=> s/(s+b) increased. It means s has increased if b remained constant.
But this can also happen when s is constant and b has decreased. Hence insufficient

b: (s+b) increased. This can happen when either s or b or both increase. Hence insufficient

Taking both a: and b: together gives us information that s has increased.

Yup Agreed, think it's C

Don't think i'm reading too much into II but it implies that (S+B) increased so as pointed, either S went up or B went up

OA?

s/(s+b) increased. It means s has increased if b remained constant.
But this can also happen when s is constant and b has decreased. Hence insufficient

True! Missed that one. It is C then.

david2008 wrote:Yup Agreed, think it's C

Don't think i'm reading too much into II but it implies that (S+B) increased so as pointed, either S went up or B went up

OA?

OA is C