[TomGuy]

from: RNC Convention ‘Rule 40’ May Have Unexpected, Shocking Result

So according to the rules, Trump is the only candidate—at this time—who qualifies to be nominated.

A similar claim that Trump has reached the magic 8 number is in this WSJ article:

40 Is the New 1,237

It seems that Trump has met the Rule 40 requirement, as of April 1. Cruz had not. Kasich would have to win all of the delegate in seven of the remaining states.

[CA Conservative]

So according to the rules, Trump is the only candidate—at this time—who qualifies to be nominated.

Cruz also has a majority of bound delegates from more than 8 states.