The following question pertain to searches within the ERIC subject $($education$)$ database

question$1$: Select a relevant keyword search strategy for this database

a$)($Students OR learners$)$ AND $($cell$*$ OR mobile$)$

b$)$ "Mobile learning" AND $("$learners$"$ OR instruct$*)$ AND learn$*$

c$)$ Mobile learning OR $($effective$*$ AND engage$*)$ OR $("$personal$*$ instruction" AND activit$*)$

d$)"$Mobile learning" AND $($engage$*$ OR effect$*)$AND $($personal$*$OR individual$*)$