Hello Maryam:
Under KL46Z there are two options and you have to select one of them. If using FRDM-KL46Z then you have to select the MKL46Z256:

About the "BOOTLOAD mode" please carefully read the next tutorials (:smileyalert: these are for FRDM-KL25Z, just have in mind that yours is FRDM-KL46Z):
OpenSDA on the Freedom KL25Z Board | MCU on Eclipse
The Freescale OpenSDA Trap: “No Device Available”, or something like that…. | MCU on Eclipse
Regards!,
Jorge Gonzalez
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