$1$ Which of the following keyword search strategies employs correct Boolean logic, and appropriate phrase searching and truncation techniques?

$($mobile learning OR mlearning$)$ AND $($engage$^$ OR motivat ${?}^{***}$ AND $($personal$*$ instruction$)$

$("$mobile learning"$)$ AND $("$engagement$"$ OR "motivation"$)$ AND $("$personalized instruction"$)$

$("$mobile learning" OR mlearning$)$ AND $($personal$*$ OR individual$*)$ AND $($engage$*$ OR motivat$*)$

$($mobil$*$ OR elearning$)$ AND $($learn$*$ OR instruct$*)$ AND $($personalized OR individual instruction$)$