an LED will light up with a specific brightness whenever the X$-$axis acceleration is above $5$g$.$ b$)$ an LED will light up with a specific brightness whenever the magnitude of the X$-$axis acceleration is above $5$g$.$ c$)$ an LED will light up whenever the magnitude of the X$-$axis acceleration is above $5$g$,$ where the brightness of the LED increases with acceleration. d$)$ an LED will light up with a specific brightness whenever the sum of the magnitudes of the three accelerations is above $5$g$.$