Chirality of 1-Pentanol and 3-Methyl-2-Pentanol

Q) Which of the following is chiral?

a) 1-Pentanol

b) 3-Pentanol

c) 3-Methyl-2-butanol

d) 3-Methyl-1-butanol

Answer: c)

If structure and it's mirror image are not superimposable then it's chiral.

But aren't 1st, 2nd and 4th options also not superimposable ?

I drew the 1st one '1- Pentanol' and took a mirror image of it. If I keep the second one on the 1st image it's no way superimposable. I may be wrong.

Also, is there any rule like if the molecule is optically active then it's chiral?