$.(5$ points$)$ Two small stereo speakers A and B that are $1\mathrm{.}40$ m apart are sending out sound of wavelength $34$ cm in all directions and all in phase. A person at point P starts out equidistant from both speakers and walks so that he is always $1\mathrm{.}50$ m from speaker B$.$ For which of the following values of x will the sound this person hears be maximally reinforced? A$.1\mathrm{.}00$ m B$.1\mathrm{.}16$ m C$.1\mathrm{.}25$ m D$.1\mathrm{.}32$ m E$.1\mathrm{.}43$ m