False. Julie could be the name of a boy.
> 2. Julia also has one brother, named Martin.
OK
> 3. Altogether, there are four siblings: three girls and one boy (Martin).
Where did you identify the third girl?
> 4. From Martin’s perspective, his sisters are all three of the girls (Julia and her two sisters).
Here's where the answer comes from (Julia and her two sisters).
More directly: "How many sisters does her brother Martin have?"
> 5. Therefore, Martin has three sisters.
OK.
So the reasoning might have come to the "right" answer but the way it arrived at the answer was incorrect.
False. Julie could be the name of a boy.
> 2. Julia also has one brother, named Martin.
OK
> 3. Altogether, there are four siblings: three girls and one boy (Martin).
Where did you identify the third girl?
> 4. From Martin’s perspective, his sisters are all three of the girls (Julia and her two sisters).
Here's where the answer comes from (Julia and her two sisters).
More directly: "How many sisters does her brother Martin have?"
> 5. Therefore, Martin has three sisters.
OK.
So the reasoning might have come to the "right" answer but the way it arrived at the answer was incorrect.