Let's check one by one option,
${\color{Blue} {(a)}}$ r=8,when we add LSB bits of both (4+4=8) should be zero and one carry but at RHS, LSB bit is 6 .so option a is wrong.
${\color{blue}{(b)}}$ r=10,it is simply when we add LSB bits of both then answer should be 8 but at RHS, LSB bit is 6 so option B is also wrong.
${\color{blue}{(c)}}$. r=16,in this also when we will add LSB bits then LSB bit will be 8,same reason as above option ,,so this is also wrong.
${\color{blue}{(D)}}$, when at r=8,10,16 is not satisfied then r>=8 is also false (only one condition is enough to make false)
So none of these option is true.