Circle

Looks to be C ,

the first statement only gives the ratio...
therefore diametre can be 3, 6, 9 ..etc not sufficient

second statement says the hypotunese is 25
therefore , we can have any pythogoras triplet
with x^2+ y^2 = 25 ^ as the answer
infact we can have 15 , 20 as one of the values ....
but in this case also diametre can be 20 or 15 ,

if we combine the two statements we know diametre will be 15
hence C

Your explanation makes perfect sense. OA - C.

However, isnt BDC a 45-45-90 triangle? Anyhow, I picked D since you only need one of the sides of the triangle to determine BC -- I was wrong.

Could one of you please explain why BDC is NOT a 45-45-90 triangle. Thanks!

BDC cant be 45-45-90 triangle

as the sides are required in 1:1:rt2 ratio

or BC and CD has to be equal, but we know that BC and CD are not equal

they are in ratio 3:4