${?}_{{?}_{{?}_{?}}{?}_{{?}_{?}}\text{a}\text{r}\text{e}\text{u}\text{s}\text{e}\text{d}to\text{b}\text{a}\text{c}\text{k}up\text{c}\text{l}\text{a}\text{i}\text{m}\text{s}of\text{b}\text{e}\text{n}\text{e}\text{f}\text{i}\text{t}\text{s}\text{a}\text{n}\text{d}\text{v}\text{a}\text{l}\text{u}\text{e}\text{p}\text{r}\text{o}\text{v}\text{i}\text{d}\text{e}\text{d}to\text{a}\text{b}\text{u}\text{y}\text{e}\text{r}\text{.}}$

Question $10$ options:

$a$

Product demonstrations

$b$