Which would be fine unless there was something else in the remainder of the question like teach chemistry has posted. If you were just asked to give a possible structure for a secondary alcohol with the formula C5H12O then pentan-2-ol or pentan-3-ol would be fine, you've been told as well it's formed from the reaction of 2-bromo-3-methylbutane with hydroxide, in which case the straight chain compound you've proposed wouldn't work.
Which would be fine unless there was something else in the remainder of the question like teach chemistry has posted. If you were just asked to give a possible structure for a secondary alcohol with the formula C5H12O then pentan-2-ol or pentan-3-ol would be fine, you've been told as well it's formed from the reaction of 2-bromo-3-methylbutane with hydroxide, in which case the straight chain compound you've proposed wouldn't work.