Aschedule of partial reinforcement in which reinforcement occurs after a fluctuating number of behaviors is called a(n) schedule. a. arbitrary interval b. variable interval c. variable ratio d. arbitrary ratio

abu bakr, was a senior companion and—through his daughter aisha—a father-in-law of the islamic prophet muhammad. abu bakr became the first openly declared muslim outside muhammad's family. abu bakr served as a trusted advisor to muhammad.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

the answer is d.index